HDD swapped from 390x wont work in T20

[JBUK]

I have several Tpads 390s, 755s and a T20. Up to now I have had no problem with swapping HDDs (all Travelstars) between machines and either loading an appropriate registry onto the swapped HDD or reloading an image from Disk Image Pro to update the new machine with a useable image or just to get the correct drivers loaded in a quick and painless manner.

BUT I have hit a big obstacle today when I fitted a 40gb HDD from a 390e into my T20. Disk Image Pro wont let me reload or do anything, saying the disk geometry is wrong - 255 heads instead of 240. Partition Magic says the same as well. They both want me to format the disk. I have 30gb of data on this disk and do not want to lose this without a fight.
If I boot to DOS the C:\ partition is seen and DIR reveals the contents and size correctly. Of course it wont boot Windows. I have - through fdisk recreated a boot partition and formatted it to no effect. Still invalid partition geometry.
Back in the 390 the HDD is fine. Interestingly the 12gb HDD from the T20 is not liked when put in the 390e either.

Anyone know what is going on here ? If I boot using the startup floppy the c: drive is seen, so the bios is happy but it wont boot windows and the powerquest utilities partition magic and drive image pro say things are so bad that a full format is needed. Both disks however work happily in their respective machines

[JHEM]

Try a FDISK /MBR on the HD when it's in the T20.

Regards,

James

[JBUK]

Thanks for the /mbr suggestion.
I have done a little looking into this. It seems its down to the bios address translation. On the T20 this is 240 heads, on the 390s and my desktop its 255 heads.
This means that the option to put the T20disk into the 390 wont work without a format and --- worse still, It cannot presumably be fitted in the desktop to quickly transfer data. [censored], is this progress ?