My lap top is Acer Aspire with XP Prof.
After finding that some programmes suddenly 'froze' after start up and, unable to activate internet or system restore in normal mode,I finally resorted to rebooting in safe mode and doing a system restore to 18thMarch i.e. the day previous to the commencement of the problem.
Fortunately this immediately solved the problem.
However I now find that each start up is similar to the start up after the system restore with the popup showing
'Your computer has been restored to( 18th March, time)... etc.etc.
Click OK
How can I correct this?

Problem now resolved (apparently after running a couple of system clean up and repair tools).

Sometimes creating a restore point will solve it. Some of your clean up tools may have already done that automatically.

Will keep this in mind for the future.Thanks.