InfoPath Dev

I created a form about a year ago and published it to a SharePoint site, and every so often I apply a few updates. During my latest update, I made a few changes in the view1.xsl file within the .cab folder. The changes are visible in the form itself if I simply open it to fill in, but when trying to enter design mode, I get the following error:

"Infopath has encountered an error. The operation failed."

 That doesn't help diagnose what the problem is whatsoever. Where do I begin to look? I need to be able to enter design mode so that I can publish my changes to SharePoint for all users to have. Any suggestions on which files to check or what to look for in the different parts of the .xsn?

Thanks in advance!

I had been searching for a few days, but not until I was selecting tags for my first post did I find a helpful tag that pointed to this previous thread:

http://www.infopathdev.com/forums/p/15981/56419.aspx

Is there something specific to look for in the .xsd that could be a dead giveaway as to what's wrong?

There's an xd:preserve tag that you can use to prevent the designer from parsing XSL and changing it. I recommend searching for xd:preserve.

For example: http://www.infopathdev.com/blogs/greg/archive/2005/03/25/Preserve-Code-Blocks-_2800_xd_3A00_preserve_2900_-and-Input-Tags.aspx