>Can i install photoshop 5.5 without uninstalling the 5.0 LE
So long as you install to two different directories within "Program Files" (assuming you put your apps there), I can't see why not. Two caveats, however:
1) If PS5.5 is an "upgrade" version, it may search out your copy of 5.0LE and install atop that. If so, then you probably have little choice.
2) Make sure you keep your file suffixes properly defined. That is, if you want jpg files to open up with your copy of LE, be sure to inform it that you don't want to modify the association. Likewise, if you're unsure if 5.5 is for you, don't modify any associations. Should you choose to remove it at a later time you won't have to re-register all the file types you had assigned with LE.
I've never tried anything exactly like this in the past, I'm just using my past experience with Adobe products. Good luck.
>If they use the same Shared files wont that give some problems?
It's hard to say. At the very least you could make a backup of your shared files directory before installing the new version, and a seperate backup afterwards. Leave the newer in place and try LE. If it works normally, feel free to delete the saved copies. If it doesn't, you can manually switch (or, better yet, write a .bat file) the directories before each run. If you don't mind my asking, what problem is it that you believe you have with the non-LE photoshop version?