Had errors with site for no apparent reason – now font is wrong in IE7

We have been experiencing problems with this blog today when first the php files stopped working. This was fixed by renaming the .htaccess file in the root directory to .htaccess.bak
Then the site was ok, but looked funny in IE7 (bigger fonts). While I was investigating this I noticed that it started to give server 500 errors and even when it was displaying the page (after ages) had multiple SQL error statements. I checked the formus and Google for an answer and the only information that I found was that it could be to do with timeouts. Since it has only started happening today i doubted this. I contacted the hosts (1and1) and they managed to bring the site back up, but didn’t tell me what they did.
Now it appears to be working ok, but looks different in IE7. The fonts are much bigger and the layout looks different – definately was like that before. Please can you let me know if you have any known issues with IE7 and viewing and if you can shed any light onto why today we had issues. Thanks!