I've run regsvr32 "name.dll" from system32 and SysWOW64 and both say it was able to load .dll but return error code 0X80004005 (access denied). I've tried running it in an elevated command prompt (right click, run as administrator) and that still returns the same error code. I've repaired the registry and restarted the computer, same error code. Any other suggestions?
The problem was that it was a Visual Fox Pro .dll and the VFP runtime files had to be moved into the SysWOW64 folder before registering the .dll.