Wait!
Before doing anything else, including a defrag, or downloading any extraneous software (other than turning the system off, removing the battery, and using a duster/vacuum to clean the system of any dust -- mind your fan, if you have it spinning too fast you can dislodge the bearings and damage the fan, for this reason I suggest a vacuum).
You have to think about this in a logical way -- troubleshooting something with the intention of resolving issues isn't some random "do this, do this, try this, try this"... there are proper steps and if you follow them you will find a resolution. I'm not trying to be rude, and I know it comes off that way, but you can spend hours following everyone's suggestions when you have already found the solution.
You said
Today, I booted up in 'Safe mode with networking' and I did not experience any crashes after using it for about 30 minutes.
Well there you go! That instantly tells you TWO things. One, and most important, is that this is not a hardware problem, though it may still be a heating issue if you haven't cleaned the laptop properly of dust! This is found true by the fact that safemode would not resolve a crashing issue if the hardware were failing, though it would relieve the load on your CPU, thus keeping it from generating a lot of heat. Two, not only is it NOT the hardware, but it is service/startup related because, as you said, no crashing during safemode (which is basically the system running with no startup items, and only basic, windows-critical services). This also removes the possibility of the problem being a BHO because the BHOs should still run with your browser. A great way to test this is to use those few minutes that it does run to download another browser, but for the moment let's just follow standard virus troubleshooting steps. (Which, believe it or not, does not involve running a virus-scanner.) That's great because you don't need any sort of fancy virus protection software or cleaner programs to fix your issue! (Thus eating up precious processing speed.)
So, you're in windows, not safe-mode. Close every program and popup you can. Right-click on anything showing beside your clock and attempt to close them as well.
Troubleshoot:
- Press the Windows Key + R, which will bring up your Run box.
- Type 'msconfig' and press enter. If it says it is disabled by your administrator, unless you have the laptop on a domain or a non-admin account (or have edited your group settings, but this is unlikely) you have a meaner virus than this tutorial covers. It can still be fixed, and I can help with that, but let's not cross that road until we get there.
- In the General Tab, select the Diagnostic Startup button. Click Okay.
- You will be prompted to reboot. Reboot.
- When the system comes up it will be in a sort of semi-safe-mode and shouldn't freeze, but it will allow you to work a bit better. Nothing against safe-mode, this is just a more controlled environment as far as what you can turn on and off.
- Now, follow steps 1 and 2 again to bring the System Config dialog back up before resuming.
- Click the Startup tab, and hover your mouse over the right-most end of the Command Column. When you see the cursor change, double-click and the column will expand to show the full command-lines below.
- Now comes the hard part. You will likely need another PC to perform this, but begin to search through each and every command. Get onto Google and search out the names of each file to see what they are and if they are in the correct folder. If you run across a file with seemingly random characters, and it is in an odd place on your system like C:\Windows, C:\Windows\System32, %USERPROFILE%\AppData, a temp folder or is a name that returns as a definite virus on Google, follow the path that the command shows (or press Windows Key + F and search your drive for the file name).
- DO NOT DELETE ANYTHING. Just rename the file and remove the extension - rendering it useless. Viruses can't magically open themselves and begin wreaking havoc, so don't worry about it. The reason we do this is because, well, let's be honest, you aren't 100% sure that this is really a virus and you may end up needing it for a program to run. Luckily nothing in the Startup tab
is critical for the system to run, so you should be fine.
- Once you are 100% sure you have removed all of the viruses, click back to the General tab and put it back into Normal startup. Click OK and reboot again.
- Test it out. This should resolve any issues you may have with viruses. After this feel free to run HiJack this, Search&Destroy, cCleaner... all of those are good... don't bother with anything else -- those three can handle it. Personally I would just use cCleaner and remove those virus entries from your startup folder. If you notice a program not working properly, uninstall it and reinstall it... don't restore the file unless absolutely necessary.
There is a small possibility that the virus is running as a service, but if it is that deep into your system it is likely you need to just re-install windows.
There, now you know how to properly troubleshoot a system without making the problem worse or randomly flailing your arms through the cyber world trying to find a fix. Happy troubleshooting.