Failure to boot after recommended update of Grub

Having installed 9.10 cleanly and successfully on top of Win 2K, via Wubi, I twice within the past 3 weeks have been recommended to update GRUB by System Update. After updating I've rebooted and fetched up hard aground each time, GNU Grub Version 1.97~beta4 failing to boot a kernel. I am left at the sh:grub> prompt, with perfunctory notice of "Minimal BASH-like line editing support". In my investigation I find no recognizable consistency in amateur advice, and am loath to experiment with imprecise or misunderstood instructions. Please identify this problem and point me to plainly articulated procedure to access or recover my Linux system. I do not want to wipe it again.

I have read that kindred errors have resulted from user failure to allow write-over of the Grub configuration file. I had no such options. I selected the four components of the Grub update as displayed in Update Manager, pushed the Install button and ultimately rebooted.

Win 2K remains fully functional, whose file system I have defragged and HDD I have checked for file integrity and bad sectors. My HDD are both EIDE but Ubuntu reports them as SD1 and SD2. All partitions are NTFS. Win 2K is installed in C:, or Disc 1-1, the only Primary partition in the system. All other partitions are Logical within Extended partitions. Ubuntu was installed in H:, or Disc 2-1.

I recognize I may be knocking at the wrong door. Like all other Ubuntu users, I have no claim against Canonical. Yet Canonical promotes Ubuntu as a universal alternative to Windows and Leopard. I am an end-user: I don't have time to become a system programmer. I would be prepared to pay for help to get over this hump, but if I had to learn the Linux/Unix command set at the outset, I would rebuild this system to run OS 10.6.

Thanks in advance.