One of our users is having a issue, he has a HP xw6400 workstation and we have seen this issue with inventor 2008 and 2009, windows xp pro with both a nvidia 1500 and then a 1700 video card, and several different driver versions.  I then completely reimaged his machine from scratch and loaded windows xp pro 64 bit and changed the system board and it worked fine for 3 days before it started doing this again.  The menus will go transparent unless you mouse over them.   He’s in direct3d mode, it doesn’t seem to happen in opengl mode but then there is a lot of flickering and the performance is not good.  We have 3 other workstations that have not experienced this that have the same hardware specs.

I have the same problem in Inv2009 (2008 was good).
HP xw4600 with Nvidia Quadro FX1500 and newest driver (Vista 32 SP1).
Wrongly, it is problem with middle key of mouse.
Function PAN does not work with .idw files (no empty).

I so appreciate your reply as I have contacted everyone about this issue and come up blank, I'm not really sure what your saying to resolve the issue though?  Thanks

Check if you have a certified graphics driver.Go tools application options, hardware, then click diagnostics.See what it says.If you haven't  got one then download one.Malenki As for the panning story first open a blank idw then open yours              and you should be able to pan.I have all the right drivers for my pc and still cant pan.(think it is a Bug)Good luck