Ads cannot be displayed. The ad module is misconfigured, failed to locate the required adserve.php file.

Take a look in your variables table -- what is the value for the 'adserve' variable? It should looks something like:

   mysql> select * from variable where name = 'adserve';
   +---------+--------------------------------+
   | name    | value                          |
   +---------+--------------------------------+
   | adserve | s:22:"modules/ad/adserve.php"; | 
   +---------+--------------------------------+
   1 row in set (0.05 sec)

That error suggests that somehow either this variable got set incorrectly, or your adserve.php file is missing/unreadable. Verify that it exists at the location specified by the above query, and that it is readable.

I'm getting the same error on a fresh install of the module.

The query suggested returns zero rows.

I manually added the record into the Variable table, and now it seems to be working.

The resulting error message said "the ad module is misconfigured" and included a link to the ad configuration page. The lack of an adserve variable suggests that you did not visit this configuration page, on which the adserve variable would have been automatically set for you.

I've added an additional call to _ad_check_install() when the above error is generated, thus no longer even requiring that you visit the ad configuration page - this error should now be auto-correcting.

Ah but i did visit that page, before even trying to configure a block or anything else. Still got the error.

Sure enough, I see the problem, the adserve variable was not being set. I have checked in a fix. Looks like I'll need to release a -beta5 soon, as that was a glaring omission.

lol, glad it wasn't me!