If you have XP (or NT, or 2000), you can make it NTFS, no sweat.
If you have Windows98, or ME, then you are stuck with Fat32, (you can still create a file that's about 4 Gigabytes, but you can't copy a file that's more than 2 Gigabytes. Some programs can't work with files over 2 Gigs, either).
I just ripped a US Phantom Menace Extras Disk, to a Fat32 disc, using File Mode with "Split to File", and it worked.
I tried it with "None", and it still worked. (The files were still well under 4 Gigs).
I dont' know if you need to have an un-split file for SubRip, or not.
But you must have NTFS for regular editing. If you split files in IFO mode, then Womble can't fix chunks any after the first one.
In any case, it sounds like you may have a bad spot on D:, and Dvd-Decrypter thinks you are running out of space.
So you need to scan D: for errors:
For Windows 98:
Right-click your D: drive.
Select "Properties".
Click the "Tools" tab.
Click the "Error Checking" button.
Put a checkmark in "Thorough"
"(performs Standard test and scans disk for errors)".
Punch "OK".
It will take a very long time. Let it run overnight if it has to.
For Windows XP:
Right-click your D: drive.
Select "Properties".
Click the "Tools" tab.
Click the "Error Checking" button.
Put a check-mark in "Scan for and attempt recovery of bad sectors".
Punch OK.
This will take a while, but only a fraction as long as it would on 98.