My iRiver T30 has always had difficulty

There may be a driver issue as I've personally had problems with my iRiver IFP mp3 player and would try to load the driver every time I connected the player to my Windows based computer.

Assuming you have a Windows based operating system, I would completely uninstall the iRiver Music Manager in add/remove programs in the control panel, restart the computer and try reinstalling the program again.