What exactly does the window say (ie WHAT is running in trial mode)
A search for whatever is running should find the files/folder, then they can be deleted after stopping them running.
Try pressing ctrl, and alt, and del (ONCE ONLY) to open your task manager. If you see the program running in there, click it to highlight it, then click end now (not shut down)
At the same time, note the name of the program running and keep it fro a reg search and after removing the string you can delete it and the whole folder.