I have a used IBM ThinkPad and use a US Robotics PC Card Modem to
Dail-Up to my ISP carrier. I recently had to replace my PC Card due to
defect after using the first one for several weeks. After replacing my
card, I could no longer use IE Explorer to go to the internet. My ISP
carrier said I needed to reload my TCP/IP but I could not since I used
a CD Upgrade of Windows 98 from Windows for WorkGroups. Frustrated, I
did a foremat C and decided to reload Workgroups, Upgrade to Win 98.
and reload my ISP program. I've done this before with no problems.
However, after loading all 8 disks of Win for Work Groups, I'm stuck
on a window that reports I'm using an Invalid System Disk, to remove
it and hit any key to continue. Trouble is, I remove all my disks
and/or CD's and I still get this message. I've rebooted and it comes
to this screen. I've used Rescue Disks, Start Up Disks, and nothing
works. I've rebooted using the F1 key and also separately the Control/
Alt key. It all comes back to the same screen. I've used the Fn key
and get a picture of the drives, but once I hit the F1 key or any
other key, it goes to the Invalid system disk window. How can I get to
a prompt so I can move on with my Upgrade to Win 98? By going to
Format C, did I remove my DOS files? If so, how do I reinstall them
without a prompt? Help

One of the floppies has "sys.com" on it.  Running "sys c: /s" will
copy the boot files from floppy to the harddrive.

But I think the Win98 upgrade doesn't require you to have Win311
installed, just have Win311 disk available.  So do this to make things
cleaner:

1) reformat and boot to floppy with CD support
2) create a folder c:\windows\options\cabs
3) copy all the win98 disks to that folder
4) run setup.exe from that folder
5) when setup does upgrade check, insert WFW floppy (disk1 or maybe
even disk3) and tell setup to look in A:

Installing from the HDD will keep Win98 from demanding you insert the
CD in the future.  To save space you can delete the AOL/ATT/MSN
internet files.

I appreciate your comment, but my problem is that everytime I start my
PC it goes to the screen with the Invalid System disk message. I
cannot get to a prompt to go anywhere else. I'm just stuck. I have no
disks in use to warrant this screen but that's what I get. Help.

I missed the first step -- you need to first boot to floppy or to CD. 
Either  WFW disk1, or Win98 CD, or your rescue disk should do it. 
It's a little tricky you might have to hold down shift to clean-boot
DOS.  Or you might need to change your bios settings to allow floppy
boot.

Because you get this error with no removable disks in your machine,
it means that the system files currently on the hard drive (C:)
are damaged or missing.

Because you get the same error when you use rescue disks etc. it
means that most likely your BIOS is set up to boot from the C:
drive first. You need to go into your BIOS settings and check the
boot order - hopefully you made a Windows 98 Emergency Rescue Disk;
I recommend using that to boot up. That means you want the boot 
order to be A:, then C: (or floppy, then HDD; your BIOS may express
itself in a few different ways). Even better might be floppy, CD, HDD
if this option is supported by your BIOS.

By formatting your C: drive you certainly did remove your DOS files,
along with all the other files. Your Win98 Emergency Rescue Disk has
a limited selection of these files on it, enough to allow the system
to boot and access the CD so that you can install Win98.

If you know how to configure your BIOS so that it looks for a floppy
to boot from first, let us know how it goes. If not, we can post some
more detailed instructions.

-- 
The Scarlet Manuka

Thanks, Scarlet.......you got it right ....it worked just fine when I
changed
  my BIOS settings once I was able to get to that screen. Took a few
boots and re-boots. Whew....came close to just junking my PC. Thought
I was gonna be stuck for life.  Boba