Photoshop File Saving
I've been using Photoshop for almost two years now and I've never had a problem saving my files as PSD files. A few days ago I went to save a file that I was editing and from that point on have had problems saving edited files. I take a basic file (e.g. FILE_123.jpg) and since I'm making several different changes to the file decided to name the new file (FILE_123a.psd). As soon as I press save the file name changes to FILE.psd... at first I didn't notice the change. After I made a second file and named it FILE_123b.psd and tried to save it the same change happened when I clicked save and it asked me if I wanted to save over the original file. Does anyone have any idea why this change is happening and how I can fix it? Thanks!

I haven't seen this issue, but try resetting Photoshop preferences. Press and hold Alt+Control+Shift (Windows) or Option+Command+Shift (Mac OS) as you start Photoshop. (If your timing was right) you are prompted to delete the current settings.
If resetting preferences doesn't fix the issue, I would uninstall and reinstall Photoshop -- it can't hurt to try.
I thought maybe you were accidentally saving to a file format other than PSD that won't accept the _123, but I couldn't replicate it.
Laura
Are you having any other issues outside of Photoshop? As big as hard drives are these days it's hard to do, but is your drive full?
I actually checked my hard drive first... it's big so I didn't think that would be the problem and it wasn't. Actually Laura, your comment made me realize that I had used the wrong kind of punctuation... the underscore does just fine in PSD! Thanks for the help!