Emax

I own a standard emax 1 rackmount, not an SE or a HD. When I purchased the machine it came with a number of floppy disks. Everything seemed to be working fine until I entered an emax SE upgrade disk which had a label on 'upgrade disc use once only'.
Since then, the sounds on certain disks have an added high frequency hiss/white noise on top of them.
Also when I try and sample any audio into it, the same added hiss occurs on top of my audio.

Since then, certain disks loaded with synths samples work without the white noise but I've tried copying these onto a blank disk and deleting the samples, and then recording audio into it, but it still adds the noise on top of it.
I tried putting operating systems (that are compatible with the emax 1) on an emax formatted disk using OMIFLOP and EMXP program. When some of these are put in the emax, they load up but the display reads 'bad bank data'. With other operating systems, they load up fine, but still the white noise occurs on top of samples/ or when recording audio.
Someone told me, that if you can filter out the high frequency sound with the low pass filter, which i can, means there is nothing wrong with the machine, you've just corrupted your disks/samples.
What I think I've done, is that when I put the upgrade disk in, this put the SE Upgrade on for the second time. As since then I can't record any audio without white noise. 

This is driving me crazy, could anyone help?

Geri