Graphic glitch/invisible ships

hi,

i've been playing this game a few hours now and suddenly all the ships are invisible. And the upgrades appear as green particle blobs rather than a small icon.
Have i pressed some key that does this or is this a glitch?

Here's an image of the problem

ah i can't post a link here, well no picture then

Did you alt-tab at any time during a loading sequence?
I recommend restarting the game and seeing if that fixes it.

yes! after a few restarts of my pc it all worked fine again.

Thx!