Photoshop saving error

When I try and save my work it will sometimes say : cannot save (file) because it is already open, try renaming, etc. However this file is not open, I try saving in different modes (jpg, gif psd,etc) and using different names but still no go. Any help on this would be appreciated.
Thanks

Are you saving across a network or saving locally?

It just started doing this a couple of days ago. BTW I can save to web but other options don't work.
thanks for the reply

I have the same problem every once in a while.
I have no idea why it does this.
I figured out that you can't save as .jpg or .gif but you are able to save as .psd.
So I always saves it like that then reboot photoshop and open the .psd again and then save it as a .jpg or .gif.
This is a very very annoying bug!

sure you haven't opened the .jpg in the background? ;)

i never ran in this bug *knocks under table*