Virus, Trojan, or Hack

Just ran Full Scan- results said unable to scan the following all in C:
\A8FGRYLL
Documents and Settings -\EZY8PL09
\LITWWL9PY
sessionstore.js (have constant pop-ups for this says run chkdsk -which does not correct or
prevent new instances of same)
MAR8B.tmp
MAR8C.tmp
Please advise

when infected files are found they are given a malware name…

files that can not be scanned or other scan errors are just that, does not mean they are infected
and there are many reasons why…

so what is the full error message given ?
what are the full path to the files ?

Thank you for the response. I will have to run again so I can give you the paths as written.
The sessionstore.js warnning in the taskbar with yellow triangle with exclamation point is a constant pop-up. As it is one of the item in Full Scan results does that mean that it is a virus.
Will run another Full Scan and post results.

Full Scan results does that mean that it is a virus.
does the popup say virus ?

can you post a screen shot ?

right click avast tray icon > show last popup > click the pin in top right corner and it will stay on screen

The Avast last pop-up says your virus defs have been automatically updated
The pop-up with the yellow triangle says
Firefox.exe- Corrupt File
The file or directory C:\Downloads ans settings\Rick\Application Data\Mozilla\Firefox\Profiles\c417ulib.default\sessionstore.js is corrupt and unreadable. Please run chkdsk utility.
Have run chkdsk numerous times - pop-up returns
Uninstalled Firefox and reinstalled pop-up returns.

The pop-up with the yellow triangle says Firefox.exe- Corrupt File The file or directory C:\Downloads ans settings\Rick\Application Data\Mozilla\Firefox\Profiles\c417ulib.default\sessionstore.js is corrupt and unreadable. Please run chkdsk utility.
are you sure this is an avast popup ?

can you take a screen shot when you see it and attach here ?

The pop-up with the yellow triangle says Firefox.exe- Corrupt File
You are apparently also running Microsoft's Security Essentials. http://answers.microsoft.com/en-us/protect/forum/protect_scanning/firefox-in-a-state-of-paralysis-until-mse-done/b444713f-ca0f-4d44-b782-b0cb78832421 It never good to run more than one AV at the same time. You should either use Microsoft Security Essentials or avast! but [b]not[/b] both.