The most frequent solutions to Access violations like Access violation at address 00000000. Read of address 00000000" are the following:

1) DirectX 8.1 isn't (correctly) installed.
Download it from MS site:

2) Try using DirectX as input/output and see if this fixes the problem.

3) You're not using the latest WHQL certified drivers for your soundcard, download them from soundcard creators website..

4) Another program is using up soundcard, try closing down all applications that run in the background , including special "soundcard" programs that are running