Logical log backup with onbar acting strangely

Hello everyone. I'm having problem with backing up logical logs for the whole week. Platform is IDS 9.40 UC5W2, Solaris 9, Sun V480. Storage manager is Legato Networker. On Monday, I've had an Informix engine hang (possibly due to a bug) but couldn't bring it down, neither gracefully nor immediately, and the oninit process didn't want to be killed, either. So I rebooted the machine and started Informix again and no problem, every piece of data was intact. Great. Unfortunately, strange things started to happen: very often I was kicked out of the shell with "fork failed" message. This turned out to be because of the number of processes per user limit was hit. After checking the process spawn rate it was obvious that logical log backup was forking more than 8 thousand processes (namely, onbar -b -l). 15 to 20 seconds after this "multifork" thing the number of processes start to drop and in few seconds they all die away. Logical log that fired backing up gets backed up normally and everything seems fine until next logical log fills up. Same thing with scheduled backups, logical log that gets backed up in the end fires the problem again. And now the spicy detail: all of this doesn't happen always, and I cannot recognize the rule. Lucky thing is that Informix works normally, no problem with it, but still, it sucks to be denied access to the system even if it's working OK. Since this is a production machine I'm quite nervous about having problems like this so any help would be appreciated. Thanks everyone! P.S. I've checked kernel parameters after reboot, no strange things there.