This is a known bug in Windows XP Service Pack 2. If haven't installed Microsoft patch yet, then do it now:
http://www.microsoft.com/downloads/details.aspx?F...7c8&DisplayLang=en
After that download and run
this registry fix. Type following lines for example in Notepad and save it as FixReg.reg. After all this, execute it.
code:
Windows Registry Editor Version 5.00
[HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\IPSec]
"AssumeUDPEncapsulationContextOnSendRule"=dword:00000002
Now you have to reboot.
There are also other causes for this problem. List of them and solutions for them can be found at
this site.
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