I have noticed recently that when using Vintage Channel VC64 my latest (user saved preset) does not work correctly.  I can see the name of the file in the drop down menu.  I can choose the name.  When I return to the track and pull up VC64 it reverts back to the next to last vst file that I created.
 
I now set Sonar 7 (with windows XP/32 bit) to scan VST plugins when I start Sonar.  This did not fix the problem.  I have been using Sonar 7 producer since it was released and never had this problem
 
 
 
Is there anything I can check?

Not quite following...are you saying the plugin loses its settings between project loads, or that it doesn't display the correct preset name at the top?

Just a thought as I too have had certain soft synth plug ins revert to default settings. This will only happen if I am working on a downloaded MIDI file. What I did find is to re assign the MIDI channel for the synth. My guess is there is system exclusive  data hidden in that channel. Sonar seems to hide some data that will not always show on events list. Sometime no matter what I do things just change back to the settings the original person set. 
If I get real annoyed I'll open the file in Cubase where all the midi data will show for me and I can delete offending data. I also used to use a freeware midi editor for this. Can't remember the name.  

bitflipper
Not quite following...are you saying the plugin loses its settings between project loads, or that it doesn't display the correct preset name at the top?

Let me try to explain:
 
I had an existing preset for VC_64.  I made some changes to the EQ only.  I saved the preset under a new name. 
 
I moved on to another track..................when I went back to the track (with VC_64) I noticed it had the "original name" preset.  The "new name" was in the drop down menu so I clicked on the "new name".  The new name was displayed as the active preset.
 
I noticed that the EQ settings did not change when I went from the "original" to the "new" name.
 
I closed VC_64 and opened it again and it went back to the "original".
 
Unfortunately I don't remember which EQ settings are saved (because the change was very slight).
 
I noticed the same thing happened with a drum kit in Session Drummer 2.  I had a kit defined which I used as basis for a new kit in a new song.  I made numerous changes and saved them.  I closed and saved the project.  When I opened it again I noticed the new kit was no longer active and it reverted back to the original kit.....