No need to shoot the computer :-)
PVS says the same here at my system, so I don't think you have to worry about that.
Have you never gotten the Voodoo card to work? The changes you have set is all that is needed to be changed. If the screenmodes are alright, and the monitor can show such high resolutions, it can be a matter of overheating of the Voodoo graphics chip.
An other option is a faulty Soundcard and/or fast ethernet card, so try running the computer with only the Voodoo card.
I had some of the same experiences as you (the computer would reset after 10-15 min, but after the first reset it was running stable), and my problems were caused by a faulty ethernet card. If I plug in the D-Link card now, I'm 100% sure that I will get some wired looking graphics on my workbench, and at the end I will only be able to use all the native Amiga screenmodes. In order to get it working again, I have to take the Voodoo card out of the Mediator and reseat it.
I have heard somewhere that the PCI card should be placed in a specifik order, but I haven't gotten that confirmed by anyone yet, so if anyone knows then say it out loud :-)