CPS-SRV-3505 error after restart

[Dev1975]

Hello everyone,

Had a strange error message come up, not seen it before and not really sure why it happened. I had to stop the Cognos services to clear the logs and enable the IPF_AAA trace file. Once the file was enabled, I started the services in order (CM, Disp) and everything was listed as running successfully. However, the Customer tried accessing the environment the following day and got this message displayed in the portlet viewer:

Unable to process the request.
CPS-SRV-3505 The target server "http://server:9080/ServletGateway/servlet/Gateway/wsrp/cps4/portlets/nav" is unable to process the request. Content is not allowed in prolog.

The Cognos logs didn't supply any further information and the error was rectified after the Customer rebooted all the servers in the environment (seven in total, with Cognos deployed in Websphere Application Server). I've trawled Google but there is no further information on this error, apart from one article from IBM which says to upgrade to 10.2 Fix Pack/Refresh Pack 1, which is already installed in the Customer's environment.

Customer, understandably, is not impressed that enabling a trace file could bring the environment down. I've enabled this trace in a number of different environments and have never had this happen before, can anyone tell me what could be the possible cause of this? The Cognos components themselves are over 3 servers (CM, Disp and GW) and all three of them have Websphere installed as well. Is there an extra step involved with a Websphere deployment or is the shutdown/startup the same as if it was deployed in default Tomcat?

Any suggestions greatly appreciated.

TIA!!