blank xwindows after working in terminal

[Linda Hanigan]

 I upgraded to 8.04 and have been having trouble with X disappearing
when I work in the terminals F1 - F3. I will switch back and forth fine
between the shell terminals and X and then randomly I will go to return
to X and I will have a blank screen. It is not a frozen screen as if you
try ctrl-Alt-bksp to restart x it looks like you have typed esc H in vi.
I have tried startx but it shows X still runing, tried killing process,
tried telinit 1 and then telinit 5 I can not get X back. I have to
shutdown for the the terminal and reboot. I had the AMD64 version of LTS
6.06 the current terminal login just says 8.04.1 I could try fixing it
by doing a clean install, but was hoping it wouldn't be necessary.
                Thanks
                 Linda