jQuery Errors

Drupal 5.5

JavaScript Aggregation disabled:
- no javascript errors, TinyMCE working, collapsible fieldsets working

JavaScript Aggregation enabled:
- "missing ; before statement" error in the aggregated file, followed by "Drupal is not defined", etc.
- the first JS error comes from the /misc/jquery.js file (the same problem when using the official jQuery 1.2.2 uncompressed or packed jquery.js file, or when using the 1.1.2 version included in the jquery_update module)
- symptoms: TinyMCE and collapsible fieldsets not working anymore
- even if I get the line/column number for this error, I'm not able to precisely identify the exact place in the jquery.js code where the problem is occurring.

Any idea? Can you try to reproduce?

Thanks