Win7- curious about wodge of strange folders

[#1]

There is a considerable wodge of folders named similar to
this "MCSRACache-4BD99C59E7" in my Windows7, created on various dates and some are empty.
Just out of curiosity I'd like to know what they are for, and if they are essential.especially if empty.
Ideas?

[#2]

cant find anything on google about these folders.
whats inside those folders that are not empty ?
are they placed in the c drive (os drive letter) or are they deeper than that?
thats all i could find but they are still none the wiser http://www.sevenforums.com/general-discussion/95819-old-odd-reg-files-more-just.html

[#3]

Screen shot of files in one folder is attached. They are no deeper than Cdrive.
I haven't a clue what the .jar extension means

[#4]

I think that jar is a java archive http://download.oracle.com/docs/cd/E17476_01/javase/1.4.2/docs/guide/jar/jarGuide.html