User warning: Got a packet bigger than 'max_allowed_packet' bytes query

Got this importing a 29k TAB'd file - huge dump of all the data then ensued, followed by the expected map columns form.

Have not gone further for fear of causing a massive catastrophe! If this is not a bug but rather something that I have to mess with in mySQL or PHP, then a more informative message would be appreciated.

Here's the first part of the message:

user warning: Got a packet bigger than 'max_allowed_packet' bytes query: UPDATE cache_form SET data = 'a:23:{s:6:\"#pages\";a:9:{s:5:\"intro\";a:2:{s:5:\"title\";s:12:\"Introduction\";s:11:\"description\";s:530:\"The Node import module allows you to import content (such as users, vocabularies, terms or nodes) into your site from a tabular file (such as Comma or Tab Separated Values files). This wizard guides you through a number of steps to configure such an import. [more help]\";}s:4:\"type\";a:2:{s:5:\"title\";s:19:\"Select content type\";s:11:\"description\";s:110:\"Select the content type for the data in the file. You can only select content types you are allowed to create.\";}s:4:\"file\";a:2:{s:5:\"title\";s:11:\"Select file\";s:11:\"description\";s:118:\"Select the file which contains the data to import. You can select a previously uploaded file or upload a new file now.\";}s:12:\"file_options\";a:2:{s:5:\"title\";s:16:\"Set file options\";s:11:\"description\";s:226:\"Enter the file format options for the file. The options specify how to interpret the file. Select one of the predefined file formats or enter the record separator, field separator, text delimiter and escape character yourself.\";}s:3:\"map\";a:2:{s:5:\"title\";s:16:\"Map file columns\";s:11:\"description\";s:97:\"For each content type field, select the columns in the file that contain the data for this field.\";}s:7:\"options\";a:2:{s:5:\"title\";s:18:\"Set import options\";s:11:\"description\";s:49:\"On this page you can set some additional options.\";}s:8:\"defaults\";a:2:{s:5:\"title\";s:18:\"Set default values\";s:11:\"description\";s:209:\"For each content type field, you can set the default value to use here. The default value is used when the field is not mapped to a file column or when the data in the mapped file column is empty for a record.\";}s:7:\"preview\";a:2:{s:5:\"title\";s:14:\"Preview import\";s:11:\"description\";s:204:\"Here you can preview the import before importing the content. If there are errors, you may want to make changes to the previous pages. Press Reload if you change the number of records to preview.\";}s:5:\"start\";a:2:{s:5:\"title\";s:12:\"Start import\";s:11:\"description\";s:104:\"Last chance to check all selected options. If you want to start the import, click Start import.\";}}s:4:\"help\";a:2:{s:6:\"#value\";s:121:\"For each content type field, select the columns in the file that contain the data for this field.\";s:7:\"#weight\";i:-50;}s:3:\"map\";a:37:{s:5:\"#tree\";b:1;s:6:\"#theme\";s:23:\"node_import_field_table\";s:20:\"#node_import-columns\";a:2:{i:0;s:13:\"Content field\";i:1;s:14:\"Maps to column\";}s:18:\"#node_import-empty\";s:40:\"There are no content fields you can map.\";s:5:\"title\";a:6:{s:6:\"#title\";s:4:\"Name\";s:18:\"#node_import-group\";s:0:\"\";s:5:\"#type\";s:6:\"select\";s:8:\"#options\";a:2225:{s:0:\"\";s:17:\"- Please choose -\";i:0;s:8:\"Column 1\";i:1;s:8:\"Column 2\";i:2;s:8:\"Column 3\";i:3;s:8:\"Column 4\";i:4;s:8:\"Column 5\";i:5;s:8:\"Column 6\";i:6;s:8:\"Column 7\";i:7;s:8:\"Column 8\";i:8;s:8:\"Column 9\";i:9;s:9:\"Column 10\";i:10;s:9:\"Column 11\";i:11;s:9:\"Column 12\";i:12;s:9:\"Column 13\";i:13;s:9:\"Column 14\";i:14;s:9:\"Column 15\";i:15;s:9:\"Column 16\";i:16;s:9:\"Column 17\";i:17;s:9:\"Column 18\";i:18;s:9:\"Column 19\";i:19;s:9:\"Column 20\";i:20;s:9:\"Column 21\";i:21;s:9:\"Column 22\";i:22;s:9:\"Column 23\";i:23;s:9:\"Column 24\";i:24;s:9:\"Column 25\";i:25;s:9:\"Column 26\";i:26;s:9:\"Column 27\";i:27;s:9:\"Column 28\";i:28;s:9:\"Column 29\";i:29;s:9:\"Column 30\";i:30;s:9:\"Column 31\";i:31;s:9:\"Column 32\";i:32;s:9:\"Column 33\";i:33;s:9:\"Column 34\";i:34;s:9:\"Column 35\";i:35;s:9:\"Column 36\";i:36;s:9:\"Column 37\";i:37;s:9:\"Column 38\";i:38;s:9:\"Column 39\";i:39;s:9:\"Column 40\";i:40;s:9:\"Column 41\";i:41;s:9:\"Column 42\";i:42;s:9:\"Column 43\";i:43;s:9:\"Column 44\";i:44;s:9:\"Column 45\";i:45;s:9:\"Column 46\";i:46;s:9:\"Column 47\";i:47;s:9:\"Column 48\";i:48;s:9:\"Column 49\";i:49;s:9:\"Column 50\";i:50;s:9:\"Column 51\";i:51;s:9:\"Column 52\";i:52;s:9:\"Column 53\";i:53;s:9:\"Column 54\";i:54;s:9:\"Column 55\";i:55;s:9:\"Column 56\";i:56;s:9:\"Column 57\";i:57;s:9:\"Column 58\";i:58;s:9:\"Column 59\";i:59;s:9:\"Column 60\";i:60;s:9:\"Column 61\";i:61;s:9:\"Column 62\";i:62;s:9:\"Column 63\";i:63;s:9:\"Column 64\";i:64;s:9:\"Column 65\";i:65;s:9:\"Column 66\";i:66;s:9:\"Column 67\";i:67;s:9:\"Column 68\";i:68;s:9:\"Column 69\";i:69;s:9:\"Column 70\";i:70;s:9:\"Column 71\";i:71;s:9:\"Column 72\";i:72;s:9:\"Column 73\";i:73;s:9:\"Column 74\";i:74;s:9:\"Column 75\";i:75;s:9:\"Column 76\";i:76;s:9:\"Column 77\";i:77;s:9:\"Column 78\";i:78;s:9:\"Column 79\";i:79;s:9:\"Column 80\";i:80;s:9:\"Column 81\";i:81;s:9:\"Column 82\";i:82;s:9:\"Column 83\";i:83;s:9:\"Column 84\";i:84;s:9:\"Column 85\";i:85;s:9:\"Column 86\";i:86;s:9:\"Column 87\";i:87;s:9:\"Column 88\";i:88;s:9:\"Column 89\";i:89;s:9:\"Column 90\";i:90;s:9:\"Column 91\";i:91;s:9:\"Column 92\";i:92;s:9:\"Column 93\";i:93;s:9:\"Column 94\";i:94;s:9:\"Column 95\";i:95;s:9:\"Column 96\";i:96;s:9:\"Column 97\";i:97;s:9:\"Column 98\";i:98;s:9:\"Column 99\";i:99;s:10:\"Column 100\";i:100;s:10:\"Column 101\";i:101;s:10:\"Column 102\";i:102;s:10:\"Column 103\";i:103;s:10:\"Column 104\";i:104;s:10:\"Column ......