On multiboot HP z600 - appears Win 7 MBR possibly modified by Updating KUBUNTU LINUX

[WB5AGF]

(Please douse your flame-throwers. Yes .. I know ... this is risky business.)

I've run into something really curious and am trying to understand what's going on.

My old HP z600 PC has been my 'main machine' since I bought it in late 2015 (so almost 10 years). It came with Windows 7 and that's what I'm still (mostly) running it with.

However ... on-and-off for years I've tinkered a bit with UBUNTU LINUX (I'll try it on a machine and then stop) and a few months ago I reconfigured my HP z600 as a dual-boot PC with UBUNTU LINUX on a different drive (buying Samsung SATA interfacing Solid State Drives (SSDs) at Micro Center (Dallas) is like eating kernels of popcorn in a movie theater .... one-leads-to-another).

Well .... I because curious about some of the other variations of UBUNTU 'out there' ...

I opened-up some space on the drive that already had UBUNTU 24.04 on it and installed UBUNTU MINT (giving each 500 GB space).

So ... yeah ... I became curious about another 'flavor' of UBUNTU .... and installed 'KUBUNTU' on a smaller SSD that was sitting around under-utilized.

So ... my HP z600 will natively boot into :

                          Windows 7 .... UBUNTU 24.04 .... LINUX MINT .... and KUBUNTU.

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All seemed happy-and-peaceful until late last night (I'm running on caffeinated beverages at present) when I went through each of the LINUX installations and ran their update process.

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Something 'went wrong' when I updated KUBUNTU LINUX.

When I tried to boot back into Windows 7 I got a screwy error message ... saying that it couldn't find the drive ...

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Long (stressful) story made short ...

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What I've found is that if I try and boot off the drive that's got KUBUNTU LINUX installed on it ... something 'bad' happens ...

The GRUB installation that 'works' is on the drive with UBUNTU and LINUX MINT.

However If I try and boot my z600 off the SSD with KUBUNTU and go look at the Boot Order .... the SSD with Windows 7 has 'disappeared'.

When the GRUB (vers 2.12) Menu shows-up ... if I select Windows 7 ... I get an error message telling me that it can't find the drive.

I did all sorts of tests .... shutting down the z600 and disconnecting drives ... then starting the z600 up with only the drive holding Windows 7. That seemed to 'fix' the problem but then ....

What I've found is that the problem 'goes away' if I power-down the z600 for a few minutes (I also disconnect the AC power cord). When I reconnect power and turn on the z600 ... all-is well ... I can boot into Windows 7 and the three flavors of LINUX.

What is my z600's motherboard 'remembering' as long as it's powered-up after being asked to boot off the drive with KUBUNTU ? ... It 'thinks' that something is wrong with the Windows 7 drive ... until power is pulled for a few minutes.

(From what I've read the HP z600 PC is only a BIOS machine ... no UEFI ... no intermediate operation. Also it doesn't seem to have a Security Boot Mode ... I found other people having problems on other machines and they were being told to make sure that their PCs were in 'Legacy Mode' and no Security Boot. From what I can tell those are not applicable on the HP z600 PC.)

Thoughts ?

- Paul