I do have FSUIPC installed, as it was used by a few scenery development tools back in the day, but most now use Simconnect. According to the log file, mine was last called back in January:)
Speaking of the log file, does this give any clue to what might be happening?
I'm not sure how a 'corrupt' library file would happen, and I've never come across anything like that before. Looking at the file, the only thing I notice is that there is one seasonal texture missing -- this was on purpose, as the hard winter Willow texture would never be used in my autogen. I can't think of any reason why FSUIPC would worry about a missing seasonal texture, but you could try adding it back. I've zipped it up, just put the WillowAgHW.dds file into the Vector Landclass\VLC_Libraries\Texture folder.
The other thing might be a damaged file on your system, so I've also included the GZautogenTrees.BGL file which you could try if the texture doesn't help. This goes in Vector Landclass\VLC_Libraries\Scenery. Maybe add a 'bak' extension to the old one first, so that it stays where it is, in case it is sitting on a damaged drive location./Download WillowAgHW.zip