1st we need to make sure you got the viruses out.
try scanning your computer with Malware Bytes
Be sure to click update and download the updates before scanning.
Also are you running a resident antivirus for future protection? If not, try avast.com they have free reg for a year. You can install this, run updates, then schedule a boot time scan to get a real deep cleaning. If you have some resident program installed though, stick with what you have. Doubling up on the antivirus can hurt your system as they compete for dominance.
Once your viruses are out, let us know if your browsers are still crashing. At that time you might try updating to a newer browser version. This could correct any longterm damage left by a particular virus, but be sure the virus is all gone first.