Enough space on the WDM harddrive?
Check inetpub/ftproot/rapport/your_package_name if there are more than one par1.img files created. WDM should split them in 4 GB pieces.
Also try these settings:
1. Authentication on Rapport HTTP Server needs to be Anonymous only
2. Authentication on MyWDM needs to be Basic only
3. In c:inetpubwwwrootweb.config add maxAllowedContentLength with value 4294967295. Setting it higher will result in 500 errors in the http logging
requestLimits maxAllowedContentLength="4294967295" maxUrl="8000" maxQueryString="8000" />
4. IISreset and restart of Hserver Init service
There is a “<" missing on front of the requestlimits line. No idea why, but if I add it, the most part of that line disappears. CG