I'm encountering a really weird problem with a relative's computer I've been working on. Unfortunately, her Win7 computer was infected with a "scareware" virus (one of the Trojan.FakeAV types). I removed it with the latest MSRT from Microsoft. However, now it seems that the hard drive is erratically slow. Sometimes programs will start up quickly, and sometimes they seem to take forever. Example: Thunderbird used to take a few seconds to start up. It still does once in a while, but she has also timed it taking as long as 2:37! This erratic behavior is the same with all other programs and operations that are heavy on disk I/O. I'm pretty sure this is a software issue for a few reasons: 1) It happened sometime during the virus infection or removal; 2) HDTune and WD Lifeguard diagnostics show nothing wrong with the hard drive; 3) Win7 boot times are not affected, indicating to me that something is going on after the system starts up.
Some observations and possibly relevant info:
1) I have also observed via Resource Monitor that neither the HDD, nor the CPU, nor the RAM are being maxed out. When something is slow, the system just sits there for a few minutes, then starts working normally for a minute, then the HDD I/O slows to a crawl again, etc.
2) The virus that the PC had interfered with programs opening, shutting them down as soon as they started and warning that "Program XYZ is infected with a virus! Click her to remove it now!" (yeah, right...) I'm guessing that part about it interfering with program startup is the key to solving this mess, but the specifics are beyond me.
3) It's sometimes so bad that (as revealed by system logs) services sometimes fail to start at boot due to timeout. It hasn't been devastating yet, but this has the potential to cause even more, and worse, symptoms.
4) The WEI (which I refreshed) doesn't show any particularly slow hardware, so again, this is some software bottleneck.
I have already tried cleaning up junk files and registry keys with CCleaner, updating the chipset drivers, running System File Checker, and defragmenting the disk. The next step to me would be a repair install from the Win7 upgrade disk, but this relative isn't very tech savvy, and I'd hate to put her through that. (She's 700 miles away, so I only have access to her PC via Remote Assistance; obviously, that doesn't work for a repair install.) Any ideas would be appreciated!
Thanks for your reply! So, even though the virus is no longer active, Malwarebytes, Avast, and/or SAS could still help remove "leftovers" that might have corrupted things? I'm in a rush, as I don't have time for more Remote Assistance before leaving on vacation next week, and I need something that my relative can run very easily on her own (since she's definitely not tech-savvy). That's, unfortunately, why I was thinking of a repair install of Windows (since sevenforums has a great, illustrated tutorial that could walk her through).
Thanks, too, for the SpinRite suggestion, but as I said this is almost certainly a software issue. I don't want to pay $89 just to further confirm that. Since my first post, I have also run "chkdsk /r", which found nothing.