NT 4.0 and Windows 7 drive fighting

[RU-B]

Precursor:

*SKIP IF UNINTERESTED*

I have a multibooted computer with 13+ entries in the bootloader. Currently, they go as follows: Win 11, 10, 8.1, 7, Vista, XP, 2K, NT 4.0, ME, 98 SE, 95, 3.1, and an Ubuntu install.

All of them boot correctly (now after much disarray), and are neatly put into a single boot menu running without metro UI but on the modern BCD framework. I use 5 real mode boot sectors for ME, 98 SE, 95, 3.1, and Ubuntu using modified versions of generated files from easy bcd (based on grub4dos 0.4.6a). For NT 4.0, 2K, and XP, I also use Easy BCD (this time unmodified) to boot into them. Each operating system works fine.

All operating systems above 2K have fully fledged drivers for everything, the base board is an IPIBL-LB (random HP board) with 4 drives + a CD drive. 

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SKIP TO:

Here's the problem: If I follow these steps, things go wrong:

Boot into NT 4.0 (no issues)

Restart (no issues)

Boot into Windows 7 (no issues*)

Once into Windows 7, after fully started, Windows 7 (but not any other operating system [ex 8.1]) will become super sluggish and slow. All drives are accessible except for the ones accessed by NT 4.0 during its boot (any time in the past, even hundreds of power cycles ago), mainly NT 4.0 itself as well as Vista and 2K. The FAT (non NTFS) drives accessed by NT 4.0 remain accessible, but NTFS drives accessed become unreadable/uninitialized in only windows 7. Trying to start a disk check on those volumes fails, and the UAC prompt takes forever to come up anyway. The system is unable to shutdown too. The current only way to fix this is to boot into another operating system and disk check anything accessed by NT 4.0. 

Here's what I want:

Windows 7 can access all drives and not be sluggish after booting into NT 4.0 any time in the past

Windows 7 can still see all partitions on all drives

Here's what I don't care about:

NT 4.0 not being able to see any other partition (actually ideally it shouldn't be able to)

 

Here's my idea:

NT 4.0 does not have disk drivers. It sees the drives (500+ GB) as 131 GB (No lba 48 support)

     - I have a disk driver I could install, but doing so seems redundant since it will only be a nightmare to reletter each drive and fix the USB drivers as well as making more partitions accessible from NT to 

       further break 7

     - If I could maybe get Vista to unletter from NT 4.0 and install NT on FAT, then it would maybe fix the issue? However I can't unletter Vista. I would also need guidance on installing NT 4.0 on FAT.

Other than that I'm clueless

 

Other info: 

I have removed all drive letters from NT 4.0 besides itself (now C:) and Vista (Z:) (it won't let me remove Vista as "boot drives MUST have letters" [this makes me confused])

NT 4.0 can only see 2 drives (technically 3 but it doesn't read the third), of which the picture has the layout.

The full disk manager layout from 8.1 can be seen as well. 

This is NT 4.0 built 1381 SP6

 

I would really appreciate some guidance! I'm lost. Genuinely no idea where to start or how one or two partitions ruins 7 completely. Clueless, however much I might know. 

 

Sincerely, RU-B

 

**Don't want any "Give up" vibes please**