Upload problem

Hi --

I recently upgraded from v.2.5 to v.3.0

I tried for the first time to upload a file. It invoked the check for conflicts search (or whatever that says exactly). Then I get a message in the log ""Can't check for file

I tried all the simle stuff I could think of. I tried exiting and reloading SmartFTP; I tried to transfer the desired file several times; I tried tansferring other files of other formats (pdf, jpg, etc.) and to other directories -- no joy. Even though I had uploaded many files in the old version without problems, I went and read the tutorial on uploading to make sure I was doing that right.

Any ideas what gives? I am dead in the water until I can upload. Thanks.