After a few more weeks I finally found the root cause for my hangups: process rasautou.exe hangs. rasautou.exe is the process which creates a dial-up connection (i think). It first occupies all my available memory and hangs my computer for about 4-5 minutes. Afterwards I regain mouse control (barely) and I can slowly open task manager and try to kill it. After 5-6 "end process" clicks, it finally dies. I have all the network fixes found here but this did not help. I do not have a solution for this. If anyone knows a solution, please let me know, because this has been going on ever since the first betas appears (for windows 7).