SAP has a number of recommended tools for debugging Crystal Reports related DLL issues. The two we recommend from this list the most is Modules and Process Monitor.
Follow this link to a KB article on SAP's website:
The Crystal runtime engine also installs a DLL by the name of CRLogger.DLL. If the following environmental variables are set, SQL connection info from the Crystal runtime engine will be logged into the directory you specify:
LOGGING_DIR = C:\CRLOGGING
LOGGING_ENABLED_ASSERT = 1
LOGGING_ENABLED_RUNTIME = 30
See this link for setting environmental variables in Windows: