Skechtup pro 8 zooms automaticly out

[kong-cept]

Hello,

yesterday everything goes fine,

this morning i open a file and skechtup zooms out until it becomes a grey empty sheet....
So i openend the file on an other computer, no problem...
I opene a new file in the trouble computer and its zooms out again..
SO i'm thinking shortest way is reinstall sketchup but I cannot deinstall it because i get this message:
the feature you are trying to use is on a network resource that is unavailable. Click ok to try again or enter an alternate path to a folder containing the installation package 'googlesketchup8.msi" in the box below... therfore i cannot install en new version !!

It's a W7-64 bit...

Please can somedbody help me urgently ?

thx