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If you've had the Alot toolbar on there its a good bet that you've got other nasties as well. That piggybacks onto other malware thats usually hidden as a free download of some kind or another
Difficult to offer advice without seeing the machine, or remoting into it
However, assuming you're running XP, run these programs, in safe mode
ATF Cleaner
ATF-Cleaner.exe - www.atribune.org
Hitman Pro
Downloads - SurfRight
Combofix
ComboFix Download
Run ALL, and run in safe mode
first one just cleans up junk, the others sanitise the machine
But resetting IE to its defaults is important, otherwise the changes made by the malware remain