md5sum of file changes...

[nilocj-d]

I have a bizarre problem. It all started when I was trying to burn an ISO image (ubuntu 9.04 desktop amd64) to a CD. The CD would burn without complaining but would not install on the target laptop.

At first I thought it was a problem with burning speed / shoddy media but after eliminating those I decided to md5sum the ISO and compare it against the values on the Ubuntu website. They didn't match. So I downloaded the ISO again and when it finished, did another md5sum. Again the value didn't match. I made a cup of tea (yes, I'm English) and checked the md5sum again and it had changed.

Over the next 10 minutes I checked it a few times and every other time I checked, it had changed. Anybody suggest a reason for this? At first I thought my machine was owned but I completely isolated the machine and it still changed. I appreciate there could be malware at work but I'm 90% sure the machine is secure. I'm wondering if this could be attributed to a dodgy hard disk or OS?

Maybe worth mentioning that I also wget'd it to a server and the checksum was correct and didn't change. I copied that iso down to my machine via scp but it arrived with a different (although unchanging) checksum.

Any input greatly appreciated... I'm running squeeze.

[nilocj-d]

I didn't get anywhere with this - ended up downloading and burning the image on another machine and problem solved. I still have the problem of md5sum returning different values for the ISO intermittently. I've tried sha1sum and am getting the SAME results with that, so I'm happy that the file isn't actually changing at least.

[Thrillhouse]

Sounds like you could have a corrupted version of md5sum if the sha1sum's match.

[nilocj-d]

Very old post but just in case anybody comes across this, it turned out I had some bad ram in the machine.