thanks for all the info…
may i ask what is the cause that will make my computer act weird where all the drive can’t open straight away but computer will ask me open with what?!
You seem to have lost the file associations, I mean, which program opens which kind of files.
I’m not sure, you need to give us more info about your computer, operational system, etc.
Did you run a full scanning with avast? Do you use other security programs (antispyware, antitrojan, etc.)?
What is the file name (and extension, e.g. .exe, etc.) you are trying to open ?
Check out this page for a number of fixes for file association problems http://www.dougknox.com/xp/file_assoc.htm
http://files.myopera.com/rejzor/files/CLASSES.zip
Unpack this and run he REG file. It will restore all file associations back to Windows XP SP2 default. In case it won’t open even REG file, open it with regedit.exe