SOAP request to proxy interfaces

Hi,

We have developed proxy interfaces and generated the WSDL using SOAMANAGER.  This we configured in SOAP UI 5.0.0 for testing.  But nowadays we are facing on challenge.  Once we load the WSDL, it will work fine.  But the same request will give below error after some time.

<env:Text xml:lang="en">Web service processing error; more details in the web service error log on provider side (UTC timestamp 20150311103533; Transaction ID 54FF1844BFE20E40E10080000A300DA3)</env:Text>

When we check t-code SRT_UTIL, it gives the below message.

If we add a new request using the same WSDL, it will work fine again.

Any idea why is this happening?