programs won't launch

[davidburd]

Suddenly, Firefox and all other browsers won't launch, and neither will Adobe Reader. I'm using Windows XP SP3.

As of Friday (three days ago at this point) I can't get Firefox to launch. It starts to load but then freezes. Or it loads just fine but freezes after I visit a site or open a new tab.

What's strange is the same thing suddenly happened to my other browsers as well. Even though I use Firefox daily, I now cannot get Chrome, Opera or Internet Explorer to launch either. (Curiously, Avant Browser seems to work!) When I look in Task Manager I see the Firefox process listed, but it's only a small fraction of the program that loads before it stops. For example, when Firefox is running normally it uses 250,000kb to 350,000kb of memory. Now it only loads 8020kb before it stops dead.

Once the program is frozen I have to kill the process in Task Manager. Then I can't get Firefox to open again without rebooting. It's as if the program becomes tainted after it freezes once. I can reboot, start Firefox and it runs. But within a minute or two it freezes and I have to reboot again. Obviously, I'm going around in circles.

What's really odd is that, at the same time, I can no longer read PDFs. Adobe Reader behaves the same way. It starts to launch and then "chokes" before it full loads. If I try again and again it does the same thing. Task Manager then shows several instances of AcrodRd32.exe all stalled at the same point. I uninstalled Adobe Reader jut in case something went bad. Now I have the same problem with Adobe Acrobat.

What in the world could be causing these unrelated programs to all stop working at the same time? Is there some piece of Windows code common to both browsers and PDF readers?

I've spent three days trying all sorts of anti-virus, anti-malware and anti-everything scans with no luck so far. It doesn't appear to be an infection. What else can it be?

 

[davidburd]

I learned more about the problem.

The failure to launch issue is affecting MS Word as well as many other programs besides browsers. It seems to be a missing registry entry for .EXE files. I found a fix that corrects the registry error but the problem comes back after a bit. My best guess is that some kind of Trojan/malware/virus is deleting the necessary lines from the registry. When I put them back, they get deleted again.

I'm doing a virus scan now in safe mode after using Rkill to stop any malicious processes (It didn't find any, though). I use Webroot along with MalwareBytes Anti-Malware, MalwareBytes Anti-Exploit, plus SpyBot Search & Destroy. I'll try each one in safe more and see what happens.