Asp .Net cache policy corrupts the heap

I have added caching profiles to my web.config for specific file types:

<system.webServer>
  ...
<caching>
  <profiles>
    <add extension=".png" policy="CacheUntilChange" kernelCachePolicy="CacheUntilChange" duration="0.00:01:00" location="Any" />        
  </profiles>
</caching>
...
</system.webServer>

Having policy and kernelCachePolicy both set to CacheUntilChange is causing heap corruption, which causes IIS to crash:

Unhandled exception at 0x00007FFRB0414D7B (ntdll.dll) in w3wp.exe: 0xC0000374: A heap has been corrupted

I dont totally understand what the difference is between policy and kernelCachePolicy and I certainly dont understand why having them set to store items in the cache would cause heap corruption. How should these be set.

*This is on an EPiServer application, but these are straight .Net settings, not EpiServer specific.