Originally Posted by mortalcombat
default defrag in Vista leaves alot of fragmented files behind- try a full defrag through Administrator:command prompt Defrag c: -w
a fragmented/error strewn drive will severly impact performance; while Corruption may result in a non-bootable system, and loss of Data (so backup).
Check your drive for file system errors and bad sectors
Your problems may also be the result of Corrupted drivers, and/or Windows itself either due to malware or Registry Cleaners-If that is the case only a reinstall/restore may fix your problems.
Again I suggest:How To Make Vista more responsive and faster
as this will determine if you have drive corruption, and scan here for malware:Antivirus Scanners & Internet Security Tools
scan will multiple online scanners, as not every antivirus will catch everything.
I suggest the following online scannners:
and Installing Avira (If using free antivirus)
For nore info on the best performing Antimalware programs , and their performance in Lab testing against current malware infections/threats see:Vista SP1 Antivirus Performance