I had to install the Post Indexer according to the Global Site Search documentation.
After I installed Post Indexer I found I could no longer login. All my browsers said "Cookies" needed to be enabled and they were on all browsers.
My tech support guys on our dedicated server found it was the Post Indexer plugin causing the issues. They disabled it (somehow) and I was able to login. I have no clue how to disable a plugin without Admin access except for deleting the files via FTP. They did not have to do that.
Anyway, have you seen this issue before?