Modifying address groups gives error ID: c105001c

[MZiggy]

Hello, I have tried amending a couple of address groups
within exchange admin and from outlook and I get the below
error when trying to apply the changes: -
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There is not enough space on the device.

Microsoft Exchange Directory System Error
ID no: c105001c
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I have over 3 GB of space on all three disks that my
exchange is installed on.

I'm running Exchange 5.5 sp4 on Win NT 4.0 sp6a

The only changes I have made to my server for some time is
that I have turned on the Storage limits warnings (last
week) to highlight when people hit the maximum, no one has
hit it yet.

Any help would he appreciated.

Thanks

Mike