The switch is a 3550 so I downloaded c3550-ipservicesk9-tar.122-44.SE2.tar to try with xmodem with the same results. If I use "copy xmodem: flash:c3550-ipservicesk9-tar.122-44.SE2.tar" it prompts me with the "Begin the Xmodem or Xmodem-1K transfer now..." I then click send file, choose the tar file, select xmodem as the protocol. The xmodem file transfer window opens and I get 1 packet and then the retries count from 1 to 9 when it times out with an error "error limit exceeded." The prompt on the CLI is I/O error. I have tried from 2 different computers and different roll over cables.

Try deleting existing images in rommon before the transfer. It seems that the flash is full and will not accept a transfer. Also .tar files are not bootable images. TAR files are meant to be extracted into flash because there are multiple files and the IOS in .bin format is included in the tar file. You will need to copy an IOS that has the .bin format.

Is this a 3550 or 3550XL? There is a big difference between the two.

if that is the case then try erasing flash and get a binary file for the Catalyst 3550 code and try the same thing.