Pictures stop expanding after Search Engine Friendly URLs switched on

[ShorehamGeek]

Hi All
I'm looking at the excellent Joomla 1.5 package (many thanks Sysman) and I've got a bit stuck. I love that an image will expand when clicked on, and can then be dragged around and clicked again to put it back.
However, when I switch on the Search Engine Friendly URLs, the images stop expanding on any but the front page. If I switch the Search Engine Friendly URLs off again, all the images expand and contract as before.
What have I done? Can anyone give me some suggestions as to what to check?
Its installed on a LAMP server (Ubuntu based). I wondered if its a problem that the joomla site is not at the root of the Apache web but in http://site/joomla?

Thanks in anticipation,

edit - just found that the Greybox gallery seems to stop working too with the Friendly URLs

[SYSMAN_MK]

See if the info here is any help.

[ShorehamGeek]

Unfortunately it doesn't seem to be as straightforward as renaming htaccess.txt and switching on mod_rewrite.

Perhaps its something with my apache installation - I'll keep on plugging.

[ShorehamGeek]

I worked through both SYSMAN's kind suggestion, and Joomla! Help Site - SEO and all is now working beautifully.

[ShorehamGeek]

Spoke too soon - if anyone else has had this problem and has any suggestions they would be gratefully received.

[ShorehamGeek]

Of course configuring the AllowOverride and access to .ht documents in the apache configuration also helps.

(bows head in embarrassment and exits stage right....)