Besides updating and performing a full scan with your current anti-virus scanner, I would also do the following;
Download and install both Malwarebyts' Anti-malware, and SUPERAntiSpyware.
One at a time, open each, update it's definitions, then run a full scan.
The other thing is Add-ons. Internet Explorer is prone to fail if bad Add-ons are installed. Not so much Firefox, but even so a bad or corrupted Add-on can affect Firefox as well.
Mark
I have a Sony PC (VGN-NR120E) laptop with Home Premium Vista. I use my computer to complete online reports/questionnaires and frequently the web browser abruptly closes. It does not matter which browser is open (Internet Explorer or Foxfire). The result is that I lose all the information that I have entered.

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