This issue occurs due to the presence of Cisco bug ID CSCeh35648.
The CiscoSecure ACS CSAuth process can restart for no apparent reason. The process can do this up to a few hundred times a day, regardless of the load.
This issue is seen when CiscoSecure ACS for Windows version 3.2 or 3.3 runs on a Windows 2000 server with SP4.
In order to resolve this issue, download CiscoSecure ACS 3.3.3. The bug is fixed in this version.
Troubleshoot software feature
Cisco Secure access control server
Crashes / reboots / traceback
CSAuth service terminated unexpectedly
Cisco Secure ACS for Windows
Access Control Server (ACS)