Creative zen xtra on windows 7

I've got my mp3 player working so that I can transfer music to and from it on windows 7 using creative media source.
However I am totally unable to access it like a hard drive, it just doesn't show up on my computer.
Which is trouble some because I've some rather big files on there that I need to delete so I can transfer more music!

Anyone know a solution?

Try and do the below mentioned steps and see how things goes:

1. Click Start, click Run, type regedit, and then click OK.
2. Locate and then click the following key in the registry: HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\USB
3. On the Edit menu, point to New, and then click DWORD.
4. Type DisableSelectiveSuspend, and then press ENTER.
5. On the Edit menu, click Modify.
6. Type 1, and then click OK.