See Borislav's suggestion.
UPDATE. I see it didn't help.
What Windows Updates were installed recently? Could they somehow cause the problem?
>Hi there,
>
>The client PCs have all been rebooted several times. I should have said that this problem started two weeks ago and we haven't managed to resolve it in that time.
>
>It's all very strange.
>
>Matt.
>
>>>Matt.
>>
>>I'm not sure if this would help, but did everyone in the company also re-boot their PCs?
If it's not broken, fix it until it is.
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