You customer complains that when he schedules a report to a UNC location the reports fail with a message "Source file error. CrystalEnterprise.DiskUnmanaged: invalid argument".
If you are lucky you are able to get from the customer information about the UNC path, screen shots and even better Trace of the server (E.g. Job Server).
In our case we got all the information but the catch is that it was censored because our customer is a government place, so we didn't get information about the exact UNC path used (only a general description E.g. Application Server).
Probable investigation flow
When getting this kind of problem your first instinct is to go to Business Object support site to find for the relvant KB article - Doing so would give you nothing.
You second action is to try and understand from the error what is the problem - Doing this would cause lots of noise because you would probably start checking if you have some parameters that were not passed to the report and also this is not the issue here :).
Your third action would probably be to ask the customer to try and browse to the UNC in which case you must instruct the customer to use the EXACT UNC path (if he knows it).
further action would have be to open a ticket, check security, Check consistent of the problem, etc (lots of time --> unsatisfied customer)
Making a long story short
The error message provided by Business Object when it fails is BAD as it says nothing about the actual problem (even with traces ON).
Our issue was that the customer configured the system to distribute schedule reports to an ALIAS name which as you know is not supported when using UNC.
The same error occurs if your try to schedule to a UNREACHABLE server.
I hope this 5 minutes post and 2 minutes read will save you 2 days of work :)