BSSV and xerces


I'm having real troubles with org.apache.xerces.jaxp.SAXParserFactoryImpl under integrated WebLogic.
Environment is E1 9.2, JDeveloper 13c, using integrated WebLogic server for tests, JRE 1.7_51.

When I run standard JP000010 BSSV test from JDeveloper IDE integrated WebLogic server starts with no errors. It generates an URL I can use to use to test BSSV itself.
I copy and paste this URL into IE address editbox anr run it.
BSSV test page appears where I select method I want to test.
I enter required infor into entry fields and press Invoke button. BSSV performs what is requested, returns data and everything lookk fine till this moment.
If I try to click Invoke again the error occurs saying that org.apache.xerces.jaxp.SAXParserFactoryImpl was not found. After that the only way to successfully run it again is to undeploy, stop WebLogic and repeat everything from the very beginning.
This all looks very strange since:
1. I'm pretty sure I haven't put nothing related xcerces anywhere. More than that, I've checked what kind of SAXParserFactoryImpl is used during BSSV functions processing and it was some weblogic...jaxp...FactoryImpl (nothing about xecrces). I've also checked and found that there is no file exist on the disk.
2. It works at the first try and stops working at the second.
3. It works if I do all this inside IDE's testing facility named Http analizer. The only "but" is that if I try to stop integrated WebLogic server without prevoius undeploy of BSSV service there are the same messages about xerces. Like Weblogic server wants it for some private actions. If I undeploy BSSV service and then stop integrated WebLogic everything goes with no error messages.

So the question to community is does anybody know what could it be and what should I check to solve this "jobstopping" issue?

Thanks, Sergey.