file extensions disappear by itself ?

I like to see the file extensions. For this, I have "hide extensions for known file types" unchecked. But, after a few days it gets checked by itself ?

How do I keep unchecked please ?

Not sure what the issue is, but I uncheck "hide extensions ..." any time I have a fresh Windows install and have never had it re-check itself. Only thing I can think of is some kind of program running in the background doing this "for your protection" ??

What kind of machine is it? i.e., name brand box, laptop, or did you build and has an OEM version of Windows? And which Windows are you running?

I agree. Something that is running is resetting that check box. It could be legitimate software, but malware is more likely. It might be time to run a few scans for nasties.

Give the PC a scan with this and see if it finds anything:

Malwarebytes

Hi All,

I was also under the impression that something unfriendly is running in the machine. This is the log from malwarebytes :

Malwarebytes' Anti-Malware 1.51.0.1200
www.malwarebytes.org

Database version: 6832

Windows 6.1.7601 Service Pack 1
Internet Explorer 9.0.8112.16421

6/11/2011 2:53:35 PM
mbam-log-2011-06-11 (14-53-35).txt

Scan type: Full scan (C:\|D:\|E:\|F:\|)
Objects scanned: 299314
Time elapsed: 1 hour(s), 49 minute(s), 22 second(s)

Memory Processes Infected: 0
Memory Modules Infected: 0
Registry Keys Infected: 0
Registry Values Infected: 0
Registry Data Items Infected: 0
Folders Infected: 0
Files Infected: 0

Memory Processes Infected:
(No malicious items detected)

Memory Modules Infected:
(No malicious items detected)

Registry Keys Infected:
(No malicious items detected)

Registry Values Infected:
(No malicious items detected)

Registry Data Items Infected:
(No malicious items detected)

Folders Infected:
(No malicious items detected)

Files Infected:
(No malicious items detected)

This is HP laptop - G72-B66US. I have win 7 ultimate 32 bit retail installed. I suspect winpatrol reverting the changes ?

OK, it's good that you don't appear to have a nasty anyway. Next, try running the System File Checker. Go to Start and type "cmd" without the quotes, then right-click cmd.exe and choose "Run as Administrator". Once at the Command Prompt, type "sfc /scannow" without the quotes. You may need your Windows 7 disc, though most of the time you don't.