Another things that should help:
I would suggest you to do the following...
1) Disable all the Scripts you have... (You can do it by going on Preferences > Scripts > Uncheck all the "little boxes" of the scripts > Apply > Ok)
2) Try again to instal the script
3) If the problem persists, take a look on script preferences again and see if there is the script you want to add isn't there. If there isn't on the list, go on the Plus! Folder > Scripts > Erase the script's name folder (in the case, the "unico" as you said).
4) Try again...
5) If the problem still occours, try reinstalling Plus! with the newest version.
NOTE: If the script were instaled after disabling all the scripts, maybe is an incompatibility with other scripts...
NOTE 2: Installing the Windows Live Messenger 8.1 don't necessary solves the problem -> I still use WLM 8.0 and don't have problems... But remember to see if the script runs on YOUR Windows Live Messenger's version.
NOTE 3: That steps are what I would do if I had this problem... I'm suggesting that... You don't have to follow them
EDIT:
As there was another guy with the same problem, MattyRid pointed this post there and I added an info there too...
See it:
quote:
Originally posted by MicroWay
Also, I've found this by using the search (click on "search" to see the results)
Just a little explanation: on the post a guy have a problem importing scripts 
Other people on that posted there, knew antother thread that a idea was suggested: Start -> Run -> regsvr32 jscript.dll (click on Start > Run >>(then write or copy/paste)>> regsvr32 jscript.dll
As I could see, reading the thread (that I pointed here), the problem was solved... Maybe is an another way of solving the problem...
Some of the scripts did not install properly... -> (Another edit... complementation) On the other post, it didn't work, anyway is a try...
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