ET crashes

So I've been playing some ET again, the only problem is that it crashes like after 20 - 30 minutes (can't tell exactly) EVERYTIME I'm in the game. After that period of time, the screen is frozen and I hear like 1 second of the last played sound files repeating over and over and over...
After that the screen just goes white and I get an error message telling me that "ET.exe needs to be shut down" because it doesn't answer anymore. Not even the ET console is there, which could tell me what the problem is, at least.

Any solutions or advice?

Thanks in advance!