Data Entry refusal

Hi Guys,
I have an infuriating problem which has haunted me when using Excel over many years and have finally decided to try and do something about it.
This is the issue.
After working on a workbook for some time, say 1 hour, the sheet suddenly stops allowing any form of data entry.
The cursor can move and select different cells but just will not accept ant data into any chosen cell.
To get over the immediate issue I have to change to another sheet, then just go back to the first sheet. DFta entry is then possible for a very short while. Then the issue re-occurs.
I'm not overly technically minded but it seems as if some sort of cache has reached its capacity and just will not allow any more entry at all.
As previously stated this issue has dogged me for many years using different PCs.
I have just bought a new PC with new MS 365. Started work and blow me, it's happened again.

Any ideas anyone?

TYIA

HG

the idea of a cache has nothing to do with data entry into cells. not that I know of anyway. a cache is a storage location. text typed from a keyboard doesn't get thrown into a cache. sounds to me that a re-installation of office might fix it.