security.config.cchfiles, and variations of them (
security.config.cch.[random numbers]etc.) are security resolution cache files.
These files are essentially a cache of the CAS (Code Access Security) demands of your application’s code. They allow the in-built security system of the CLR to resolve the security demands of your code slightly quicker.
You can safely delete these files, and this will result in your application’s initial performance next time around to be slightly slower, however, the CLR security sub-system will eventually re-generate these files.
There was a known issue that could arise from this process, “FIX: Error message when you try to run a Web application that was built by using the .NET Framework 2.0: “Overwhelming changes have occurred” however, this applies to .NET Framework 2.0 and may or may not still apply with .NET Framework 3.5 SP1 (which you’re using with VS2008 SP1).
It’s perfectly normal for there to be many reads/writes to these files, however, if the reads/writes seem excessive and to the point where you’re experiencing lock-ups I would look into either reviewing your code (assuming you have many calls to demand specific security actions or equivalent), or examining the configuration of your Runtime Security Policy as set within the .NET Framework Configuration Tool (Mscorcfg.msc).
.net cache files – ok to delete