I ve sent a tip on that error a yesterday or the day before.
There probably is bad cache file inside the library You use - simply go to the directory /folder where it is stored - and search for a file which name either is "cache" or contains such string... and simply delete the file
It is autognerated on load of the library it is some kind of precompilation of scripts.
Even one such bad file inside one of the loaded libs can mess with the previews.
Regards,
Piotr Dobrowolski