Problem with a partition

I have a hard disk with two partitions. I was using System Commander but suddenly one of my partitions stopped showing on Windows XP. But when I try to access it with System Commander it shows the partition with all the files on it. System Commander has an option to copy those files to another partition, but I don´t have enough space on my other partition (the good one) and it seems I can´t choose the files I want to recover.

The point is, aparently the partition is OK, but Windows isn´t showing it. I tried a partition recovery utility but all it recovered was trash. What can I do?

It sounds like something is corrupted with your Windows . I would try
to do a system repair with the Windows Setup disk. Boot from the CD,
let it go through all the motions. When it get to the screen asking you
to install Windows there should be an option to repair your current setup.

Look in your device manager to see what it says about that partition

OK, let me update you on the situation. I have two hard disks, lets call them Disk A and Disk B. System Commander screwed Disk A and made it dissapear from Windows.

After trying a lot of utilities I decided that the partition was lost so I decided to format it. I formated it with System Commander. It leaved Disk A with an OS/2 partition. Then I formated it from the Windows XP installer. It did the trick and Disk A was functional again, altought I losed all the information on it.

The problem is that before doing the Windows installer thing I loaded System Commander for a last time to see what was inside the Disk A before formating it (since I could only access it from there). After doing that my Disk B was rendered useless too!! There must be some kind of bug on that program that causes it to change the HD file system.
In the case of Disk B, it could be seen from Windows, but device manager said it had a RAW file system so I couldn't see what was inside of it. This time I tried another utility (GetBackData for NTFS). It took like one hour and a half but I could recover all the information on Disk B.

So the situation was kind of resolved at the end. Anyway, thanx for the advice you gave me. And as a recomendation, never use System Commander, unless its the very last version available and you really need it.

Good to hear that you got back your data. Important point is always keep backup. We never know when the system will behave in unnatural manner. Some time back I also lost the data due to software malfunction, since then I always keep back up.
I was able to recover the data almost 90% of it by using Stellar Phoenix Windows data recovery software. Lost some of the data due to corruption.
So I learn from my mistakes and keep regular backup since then.