I have just experienced the issue found here, http://drupal.org/node/282305, but on a clean Drupal 7.15 install with the latest version of Token installed, 7.x-1.3.

I ran into the issue after importing a bunch of content with Feeds. The content already existed, and before I installed Token contrib, the Token API in core allowed me to set "Allow user-entered tokens" on a few Link fields. I set this for some of my fields, and didn't think much of it.

I didn't actually install the Token contrib module until about 30 mins ago, which started giving me an error specifically on URLs containing /node. At that point, I was unable to view my homepage, and any other nodes on the site without getting an error 500. I wish I could give you more details of the specific error, but Drupal gave no specific error in the log, and I just got an error 500. I found the above error and saw that others were able to fix the issue by disabling the user generated tokens selection. It seems tied directly to Token API rather than Link module, but at least it works for me now.

I will see if I can dig up some error logs from my server, but this error was definitely triggered by enabling that checkbox, as after I disabled the checkbox on fields that it was enabled on, I was able to view my nodes again just fine.