5. Adapter installs fine, I go on the internet - streaming video and file downloads complete.
6. I open up a file download - .ZIP, .exe etc and most of the time i get some sort of check sum error which means that the file is corrupted. Alternatively a setup process kicks in and I get an error half way through. The worst part is that this is what happens to windows updates. Some go through and some die horrible resulting in blue screens etc.
Now if I download a file and copy it on a usb stick, than run it on my laptop the file works fine. This makes me doubt that the problem is in the wireless adapter.
I ran tests on SSD drive and memory tests, everything passed with flying colours. I doubt it's RAM or the SSD because I have installed Unreal Tournament and AION from the CD - which means that nothing was downloaded. These games run fine for hours, that's why I don't think that the fault is in hard drive or ram....
What can be a cause of this bizzare behaviour? How do I confirm the cause of the problem?
Check the MTU setting in the router and try reducing it from the usual default of 1500 by increments 100 and test with the same files (if possible) and try to reach a safe figure which doesn't cut performance.
There's a free program called TCPOptimizer which may give you some guidance on correct settings.