Windows XP Home Installer file infected with win32: Hiddenstart PUP

Viruses and worms
1

I’m running a Toshiba Satellite notebook Intel 1.86 CPU 1.5 RAM. I have Win XP Home installed 3-SPK w/ all updates. I’m using Avast 7.0.1466 Home Free that has been updated from 4.6 for two weeks. No other new programs have been installed. Right after upgrade I ran a boot scan that resulted in zero flagged files.
This evening I ran another boot scan and one file was flagged as infected with Win32: Hiddenstart PUP. The following line is from the log file:

C:\WINDOWS\Installer\a2f953.msi|>ISSetupFile.SetupFile5 is infected by Win32:HiddenStart [PUP]

I tried to move it to chest, repair, and delete it but Avast 7 would not allow any actions.

Q: What is it? How will it affect the system? How did it get by the Virus system? How can it be removed?
I have been having Virus problems for the last year and have had to do 3 reinstalls. I had just got a 1T USB HD to do a total backup when this flag came up. I still have not been able to track down how these things are getting into the computer nor is my computer tech.

Any help or direction would be of great help. Thanks.
Terry

2

PUP= Potentially Unwanted programs.

Means that files/applications detected as PUP is not malicious by itself but it can be used for malicious purposes.

Avast! shields dont scan for PUP’s in real time by default so no doubt it came through

to enable PUP scanning in avast!

Open avast! User interface>>File system shield>>expert settings>>sensitivity>>check the box that says scan for suspicious files and PUP’s

Next,to remove this follow this guide and attach all logs here:
http://forum.avast.com/index.php?topic=53253.0

Also,could you upload the detected file to Virustotal:
www.virustotal.com
and post the link to results please.