Hi, I have developed a module called XMLdb based on a version of XML module from V2.0 of DNN.  When the Core XML/XSL module is install on DNN 3.3 or better, the Modules setting values for the XMLdb module is impacted. 

In the 03.03.00.SqlDataProvider file of the install exists the following SQL commands

UPDATE {databaseOwner}[{objectQualifier}ModuleSettings]
SET    SettingName = N'XML_XmlSourceUrl'
WHERE  SettingName = N'xmlsrc'

UPDATE {databaseOwner}[{objectQualifier}ModuleSettings]
SET    SettingName = N'XML_XslTrans'
WHERE  SettingName = N'xslsrc'

These commands rename all modulesettings records where the SettingName is ether xmlsrc or xslsrc regardless of the module's type.  So any XMLdb modules will also have the SettingName changed.

The correct for this is to add an additional where clause to the above commands as follows

UPDATE {databaseOwner}[{objectQualifier}ModuleSettings]
SET    SettingName = N'XML_XslTrans'
WHERE  SettingName = N'xslsrc'
AND ModuleID in (Select ModuleID
 from {databaseOwner}[{objectQualifier}Modules] M
 join {databaseOwner}[{objectQualifier}ModuleDefinitions] D on M.ModuleDefID = D.ModuleDefID
 where FriendlyName = 'XML/XSL')

This additional clause will ensure that only the XML/XSL modules are updated in the ModuleSettings

I will post this issue on the DotNetNuke Support WebSite.

If anyone encounters this problem with XMLdb, please contact me at XMLdb [at] Tressleworks {dot} ca. Also, I would like to thank Vinenc Masanas who orignially reported this issue to me

Hope this helps 
Paul.