I am not sure how I did not find this thread. It did not come up when I did a search for "TL2000" on the forums. Regardless, thanks for merging the post.
Here is how I resolved my issue (with Dell support!
uninstalled the tape library and rebooted the server for good measure
opened C:\Dell\Drivers\7NH5M\7NH5M\Windows2008x64_R2 (I had already obtained the driver that Dmitry references above)
Voila! Veeam works like a charm with my Dell PowerVault TL2000
I was seriously impressed with Kyle @ Dell support. Don't discount them too soon, Gostev!
Apparently Veeam is like Microsoft Data Protection Manager (with the TL2000) in that you need to use the nonexclusive driver. From Dell's readme.txt for the 7NH5M driver:
install_nonexclusive.exe should be used by applications permitting multiple open handles from a host to a drive to exist at the same time.
I hope this post helps someone in the future!