Is your "l drive" physically connected to your computer i.e. not on a network? Your image files can be on a network drive but not the Catalog File and the Previews files.
Hint when you copy / move your Catalog file (the one with extension .lrcat) to a folder of your choice on your "l drive". Go to the l drive and double click on the catalog file and that should boot Lightroom and then Lightroom will "know" where the Catalog file is located.
Thanks DdeGannes. The I drive is a second hard drive within the computer. I'll try what you suggest.
Seems to be behaving itself now - thanks a lot for the tip!