Usually the support staff will ask you to provide log files to troubleshoot a problem. Here's how you can create such logs:
In config.php, edit the following lines:
We set here 4 as the logging level, but you can put any number between 0 and 5, which have the following meanings:
0: No logging
1: Security attacks attempts, errors and important messages (recommended level)
2: Reserved for debugging (only logs if DEBUG is true in config.php)
3: + Warnings and EventLogs, VIEW/ACTION and Request URIs and URI redirections and POST/COOKIE values
4. + plugin events, curl requests, some function calls with their parameters, etc.
5: + include suppressed actions and SMTP traffic.
6: + Action responses (ajax,serialized,XML (as array)