Remote LONGTX with no userthread in 9.30 UC6 W4

Hello all. We use here IDS 9.30.UC6W4, running in SunOS 5.7. Both Informix and Solaris are 32 bits. For the second time we have reached a situation where the instance shows a LONG TRANSACTION marked with flags --H--G and userthread 0. When this instance is started, after the fast recovery it instantly is signed as OnLine (LONGTX) and the second header line shows the instance as blocked. On our message file, there is an indication of a distributed transaction as follows: 17:42:04 Aborting Long Transaction: tx 0x83dceef8 no user info due to XA or distributed (2-phase commit) transaction 17:42:04 Aborting Long Transaction: tx 0x83dced28 no user info due to XA or distributed (2-phase commit) transaction 17:42:04 Session completed abnormally. Rolling back tx id 170, flags 0x108463b 17:42:04 Session completed abnormally. Rolling back tx id 80, flags 0x108463b 17:58:09 Aborting Long Transaction: tx 0x83dceb58 no user info due to XA or distributed (2-phase commit) transaction After this, the instance is blocked, and the following appeared in our message log: 20:29:30 Logical Recovery has reached the transaction cleanup phase. 20:29:30 Logical Recovery Complete. 0 Committed, 0 Rolled Back, 3 Open, 0 Bad Locks 20:29:31 Dataskip is now ON for all dbspaces 20:29:32 Checkpoint Completed: duration was 1 seconds. 20:29:32 Checkpoint loguniq 109671, logpos 0x15018 20:29:32 Maximum server connections 0 20:29:32 Blocking on XA transaction, tx 0x83dceb58, till it is cleaned up. 20:29:32 Blocking on XA transaction, tx 0x83dced28, till it is cleaned up. 20:29:32 Blocking on XA transaction, tx 0x83dceef8, till it is cleaned up. 20:29:32 On-Line Mode The only solution was to call 24x7, and the problem was solved. They used an utility to clear the transactions. Unfortunatelly there was a second occurrence yesterday. Additional information: Applications using Oledb with .NET. Applications using ODBC. Applications using ESQL/C. The only distributed transaction is a .NET application that opens two connections with the same instance but two different databases. Does anyone has any ideas of what might be causing this situation? Thanks in advance rdtbra.