Hi, In my application, I'm parsing the XML data using LibXML parser, based on the Apple's 'XMLPerformance' sample code. I'm using the same logic of downloading and parsing in a separate thread. But I've been getting this error every time I use the 'LibXML' parser. The debugger stack is as follows: #0 0x914df1c6 in mach_msg_trap #1 0x914e69bc in mach_msg #2 0x970d30ae in CFRunLoopRunSpecific #3 0x970d3cd8 in CFRunLoopRunInMode #4 0x31699d38 in GSEventRunModal #5 0x31699dfd in GSEventRun #6 0x30a5dadb in -[UIApplication _run] #7 0x30a68ce4 in UIApplicationMain #8 0x00003dfe in main at main.m:31 I'm unable to figure this out, as to what is causing this error. And there are times when this error doesn't pop up at all and the app works pretty fine. And, for the testing purpose I've also deployed 'NSXMLParser' which parses the same data without any errors as such. Kindly help me out to fix this issue. If anyone needs more info let me know. Thanks for reading through.