Error with XWE

I just got XWE, but since I got it, I have not been able to upload the map I'm working on. It comes up with the error
"File could not be opened (Error 32)
C:\program files\doom2\Invasionmap.wad"
I was able to open the Doom2 file, but not this one, or any other one. What's wrong with it?

Possible solutions:

1) You're trying to open your project with XWE while with Doom Builder the same wad is opened.
2) File has been moved into another directory.

If it's not the cause, then I don't know...

Has it become corrupted somehow? Is it a valid .wad file?

Does it open in your port of choice?

Well, the first guy that posted was right. I had to close down DB...Sorry =P I'm new to this, and kinda stupid.