If you have ever received this error while performing an stsadm –o export of a site in your SharePoint farm, there is an easy fix I discovered that fixes the problem.  You can view the step-by-step instructions on Joseph’s blog post about the issue.  It worked great for me!

His solution is this (there are screen shots and more details in his post):

1)  Create a copy of C:Program FilesCommon FilesMicrosoft Sharedweb server extensions12TEMPLATEFEATURESTSATypesFields.xml (you know why.)

2) Open Fields.xml

3) Replace all instances of “{ (quote-curly-bracket) with ” (quote)

4) Replace all instances of }” (curly-bracket-quote) with (quote)

5) Save Fields.xml and retry the export operation.