virtualbox.org

I often find the time is different between host and guest by 5 mins sometimes (wish I knew why, which makes problem number 1). I can see the guest making gradual adjustments to catch up, but I’d prefer the instant correction, which by default is only done when the difference is more than 20 mins.
I issue the following command to keep the drift manageable under 5 seconds.
VBoxManage guestproperty set bluebear "/VirtualBox/GuestAdd/VBoxService/--timesync-set-threshold” 5000
However this doesn’t work – When I try adjusting the host clock by a couple of mins, the guest still only adjusts gradually. Could you assist please.
I am using windows xp in host and guest. host is on 24/7

Did you install guest additions in the guest? The time sync commands will not work without it.

yes they are present

Assuming that you have as Don said installed the guest additions:

Decrease the threshold until it behaves. I use 1000 for the one that misbehaved for me. (by the way this seems to be the guest OS that is actually causing this issue since I have plenty that don't exhibit this issue).

its hit and miss then is it. Can Iset the value to 0?

I wouldn't, 1000 is almost instantaneous for mine.

yes this works now, thanks.
But I now have some extra (mistyped) properties, which I have tried removing with "VBoxManage guestproperty set " which the manual says will delete them, it doesn't, all it does it set the value to blank

Blank statements are of no concern. Unless you know what you are doing I would leave everything alone.
Remember the phrase "if it ain't broke keep working on it until it is"?
Really, since there are no values they will not be an issue.