[SOLVED] Theme Change Causes Problems

Hi Flynn,I had a problem with thumbs & Atahualpa 3.4.5, (on wp2.9.1 @ travelhorizonstyle.com.au). Also my host says I'm using too much cpu, so I changed themes, and then back again to Ata.

Please help as now
a) ALL my categories only display a maximum of 3 posts, and
b) all posts have comments turned on, when they were all turned off before. When I edit a post, the []Allow Comments box is off.

It looks like the index file's loop has somehow been modified when I viewed 3 other themes (default, swift & afterburner). Should I re-install Ata (and loose previous mods again?)
Kind regards, Joan.