I’ve been trying to run a virus scan all day, but I’m afraid there may be a virus preventing me from running the scan, I just don’t know. I tried running a quick scan, but after two hours it still said that quick scan was 0% completed… Also the scans won’t run any faster than 20.6KB/ps… It seems like my computer is running slower and slower every day; does anyone know what’s wrong? I don’t speak computer very well, and I’ve had this computer for about two years and have been able to keep it virus free thanks to Avast, but now I just can’t figure out what’s wrong. I even tried re-installing avast and that didn’t help either… Please help… 
Please attach your logs. (AdwCleaner, MBAM, OTL and aswMBR…!!)
Instructions: http://forum.avast.com/index.php?topic=53253.0
do you have any other security programs installed?
No, I have no other antivirus.
ok…continue with the guide Asyn gave you and attach the logs…not copy and paste
when done an expert will be notified and take a look…
I think I got everything. I hope I did it right.
Does the scan freeze at any particular point ?
Warning This fix is only relevant for this system and no other, using on another computer may cause problems
Be advised that when the fix commences it will shut down all running processes and you may lose the desktop and icons, they will return on reboot
Run OTL
[*]Under the Custom Scans/Fixes box at the bottom, paste in the following
https://dl.dropbox.com/u/73555776/OTL_Fix.GIF
:OTL
FF - prefs.js..extensions.enabledAddons: browserprotect@browserprotect.com:1.1.3
O3 - HKLM\..\Toolbar: (no name) - Locked - No CLSID value found.
O3 - HKU\S-1-5-21-1901354078-3903908484-3816544692-1001\..\Toolbar\WebBrowser: (no name) - {2318C2B1-4965-11D4-9B18-009027A5CD4F} - No CLSID value found.
O3 - HKU\S-1-5-21-1901354078-3903908484-3816544692-1001\..\Toolbar\WebBrowser: (no name) - {BF7380FA-E3B4-4DB2-AF3E-9D8783A45BFC} - No CLSID value found.
:Commands
[resethosts]
[emptytemp]
[CREATERESTOREPOINT]
[Reboot]
[*]Then click the Run Fix button at the top
[*]Let the program run unhindered, reboot the PC when it is done
[*]Open OTL again and click the Quick Scan button. Post the log it produces in your next reply.
Are you asking me to run the OTL scan again and then tell you if it freezes?
Yes run the fix and then run a quick Avast scan to see where it freezes
Well, I ran the fix scan, accidentally clicked the start button while it was running and it froze my computer for an hour and a half, making me force my computer to restart. I tried the quick scan once I got over my mini heart attack after my computer decided to black out my screen upon reboot and tell me that something from some registry was deleted. Anyway, the quick scan has been running for 10 minutes and is running at a speed of 7 kbps… It’s not freezing on any file, it just won’t run faster than 20.6 Kbps…
Go to the antivirus settings > performance and toggle the switch … Speed up scanning by reading the files in the order they were placed on the disc
Does that help ?
No, that didn’t help either.
So all we have now is a very slow scanning rate
Have you defragmented your disc recently ?
Yes, i tried that quite a few times…
Left the scan running for a while, after 30 hours it had only scanned 2 MB… My programs are now taking forever to start up and they often become unresponsive…
Download Windows Repair (all in one) from this site
Install the programme then run
https://dl.dropbox.com/u/73555776/waio%20start.JPG
Go to step 3 and allow it to run SFC
https://dl.dropbox.com/u/73555776/waio%20step3.JPG
On the start repairs tab click start
https://dl.dropboxusercontent.com/u/73555776/waio%20startrep.JPG
Select the following items and tick restart system when finished
That didn’t work either.
When you reinstalled Avast did you also use the uninstall utility ?
I just uninstalled it from the programs menu.
OK lets fully uninstall
Download Uninstall Utility to your Desktop.
Download the correct version of Avast
http://files.avast.com/iavs5x/avast_free_antivirus_setup.exe
http://files.avast.com/iavs5x/avast_pro_antivirus_setup.exe
http://files.avast.com/iavs5x/avast_internet_security_setup.exe
http://files.avast.com/iavs5x/avast_premier_antivirus_setup.exe
Disconnect from the net
Uninstall Avast via control panel
[]Run aswClear
[]It will offer to reboot to safe mode … Accept that
https://dl.dropbox.com/u/73555776/aswclear.JPG
[*]Once it has rebooted to safe mode
[*]In the Select Product to Uninstall dropdown choose the version of Avast that is on your system.
[*]Press Uninstall
[*]Once complete reboot your system to Normal Mode
[*]Reinstall Avast