QGIS » QGIS Application

I have qgis 2.8.1 installed on 2 laptops (win7 64bit) and a brand new desktop computer (also win7 64bit). On the two laptops it works flawlessly. On the desktop pc however it doesn't. When I try to do some geoprocessing like spatial query or pointcounts I get an error message and the program shuts down. This happens every time regardless the project or source data. The sad part is, the same started happening on my old desktop computer (also win7 64bit) after I updated from qgis 1.8 tot 2.2 (new harddisc on my new computer so no remnant of an old installation there). Since I try to minimize the installations of windows (and other software) on my desktop computers I was wondering if the geoprocessing tools use anything outside of Qgis, probably embedded in windows, to work? Now this has been going on for me for at least 6 months and I tried to find other bug reports regarding the same issue (admittedly since english is not my main language I might have used the wrong keywords in my search). Today I got so sick and tired from switching from my desktop to my laptop and vice versa a few times a day that I made a bug report here. when I get home from work I will upload a screenshot from the errormessage.

the screenshot I uploaded is from a project where my laptops work fins and my desktops pc chrashes. The points are pointdata originally from a CSV file but saved as shape. The raster is a vectorlayer and in this case I tried a count unique point in polygon algorithm.