InfoPath can be a tough beast to tame as it is a bit of an odd document type. Unlike regular file types such as MS-Word or Excel, InfoPath does not store a form's layout alongside its data. In addition it allows extensive custom development as well as external data connections. In other words it is more like a development environment, not a file format.
If you are experiencing errors during the conversion of InfoPath files then, as a first step, check out the InfoPath troubleshooting Guide, which contains solutions for 99% of the most common problems.
If you are still experiencing problems after going through the Troubleshooting Guide then please execute the following steps:
Add the following to the appSettings section in the Document Converter Service’s config file and restart the service:
<add key="Muhimbi.IO.TempFile.DisableDelete" value="true" />
This will prevent temp files from being deleted.
This config file is located in the folder where the Conversion Service has been installed in. A handy shortcut can be found in the Start menu.
Convert a problematic file.
This file will remain present in the Document Conversion Service account’s temp directory. The location of this directory can be found in the Document ConverterService’s log file (you may need to enable Debug logging). On Windows server 2008 this directory will be something like _C:\Documents and Settings\<service account name>\Local Settings\Temp_.
Log in using the account used by the Conversion Service, navigate to the InfoPath XML file in the Temp folder and open it in InfoPath. This should highlight any configuration problems. There should not be any warning or error messages when opening the file in InfoPath.
Remove the key again from the config file when you are done with the troubleshooting process or your temp files will not be deleted and your hard disk may fill up.