The list of saved sessions in Putty are not appearing properly in the "Default Settings" drop-down in the configuration dialog. I think before they used to be-- one possible caveat might be that I am not using my original copy of Putty, but rather "Portable Putty", release "PuTTY Xming-Portable 126.96.36.199" by Simon Tatham. This is a variant which does not store sessions in the registry, if that makes a difference. However, this IS the version of Putty that I have registered with your mRemoteNG program and whenever it pops up the PuTTY configuration dialog in the Tools->Options dialog, this is the version of PuTTY that pops up. I don't know if this makes a difference. Portable PuTTY stores its sessions in files rather than in the registry.
This is a bug / misfeature / whatever that is affecting my ability to use mRemoteNG for work purposes!! So I personally place a pretty high importance on getting it fixed!
Windows 7 / PCx86_64