hi, i have developed an NPAPI plugin in Visual C++ which uses sipxtapi functionalities. I have tested it on WIN-VISTA, WIN-XP and everything goes fine but when i test my application on WIN2K (version 5.00.2195), it gives an error after closing the firefox The instruction at "0x0309f41e" referenced memory at "0x0309f41e". the meory could not be "read". click ok to terminate the program. I tried googling on the issue and finally i got the following links: http://support.microsoft.com/?kbid=... http://support.microsoft.com/kb/267... The link suggested that it was a bug in WIN2K and you have to get latest WIN2K service pack...i downloaded the latest service pack(SP4) for WIN2K , ran the setup and then confirmed that my WIN2K has SP4 installed in it. Now, sometimes the error comes on closing firefox while sometimes not....i am not able to understand that why this is happenning? Thanks in advance Himanshu