Explorer and firefox both crash on startup

Hi all,
I know this is my first post, and I feel bad asking for help... then again, I have a feeling this happens all the time. Plus, I'm at my wit's end here. Also, forgive me if this is in the wrong section.

Okay, firstly, I have been using both firefox and explorer perfectly fine for years, and that includes the somewhat-recent firefox 3. I was using firefox yesterday fine, until i closed it (as you tend to) after normal browsing. Except, when I tried to start it up again, it came up with the error message: "we're sorry, firefox had a problem and crashed. we'll try to restore your tabs and windows when it restarts", followed by something about sending reports to mozilla, and I get two options "Quit firefox" or "restart firefox". If I click restart, it just loops the process. This happens immediately every time I try to start firefox, I don't even get a glimpse at the actual browser

With explorer, when I try to launch it, I get the standard "internet explorer has encountered a problem and needs to close. we are sorry for the inconvenience" error message.

Furthermore, I know this isn't an internet connection issue, since I MSN connects just fine. Also, all the anti-virus and anti-spyware programs can also connect to the internet to update.

I used AVG to scan the computer whilst in safe mode, and it did find four viruses, but healing it still didn't help.

I have attached the relevant logs from SAS, MB, combofix and MG.

Thanks for your time.

 

...The final log.

 

...Sorry to triple post, but I forgot to mention something. Recently, an odd problem has been happening. One day, I noticed that the 'show hidden files' option doesnt work anymore. When I try to tick it, it just goes right back to 'do not show' automatically. I thought I removed the virus causing it, and I fixed this problem by fiddling with the registry, but just now it happened again. I was trying to access with firefox application data, and all of a sudden, I couldn't view hidden files anymore (even though, about a minute prior, it was fine).

 

Thanks for your reply,
Actually, I managed to fix the aforementioned firefox/explorer problem by simply doing a system restore to a point when it still worked. I can't believe I didn't think of that earlier.

It also turns out I was infected with kavo.... which proved to be a bit of a doozy to remove, but I got rid of it eventually.