Joice,
Due to the number of parallel processes running and system CPU and Memory limitations some IDocs process slowly or hang. Normally restarting the job should fix the issue but if it happens repeatedly have the BASIS team monitor SM58 and look for unusual patterns.
If you have access to SM58 in the source system then select the lines starting with IDOC_* and Execute the LUW. There may be many entries so only choose your target system.
I hope this helps.
Regards
-Sid