critical error help

[Melita]

http://puu.sh/ocryd/458eb6a1d9.jpg
i got this error when i try to sell items or throw them in the ground, any solution?
i already did a full check.

[smn]

What OS are you using? If it's win 7 you probably need windows updates for XML. I would suggest the following:

Microsoft XML Core Services 4.0 Service Pack 2 (KB973688)
Microsoft XML Core Services 4.0 Service Pack 3 (KB973685)