If any one was wondring how I did it, this is how.
I made a new file called. "pop3.reg"
and put this code in side it.
[HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\App Management\System Programs]
Then I click it and it asked me if i wanted to add that to the reg and I click Yes then Ok.
then in the pop3 plugin config I replace "msimn" with "thunderbird" and now it works.