Zen-cart Admin unwanted Log Offs

I search the forum, but did not see this issue anywhere else, my apologies if this is a duplicated post.

We are running Zen 1.2.6.

I have an issue with my website which I am hoping may be relatively easy to correct.

When I log into the Zen Cart as admin and perform a search on merchandise ( catalog -> categories/products then
enter a string into the search box and click on "search" button ), I am immediately logged off from the Zen cart.
-> I can not perform searches.

Similarly, if I try to sort customers alphabetically ( customers -> customers, then click on the ascening (asc) link) - I immediatley get logged off.
-> I can not perform sortations

Other searches will also cause an immediate log off.

I do not remember having this issue, so I think it is "relatively" new.

I checked the session ( configuration->sessions ) session_directory path and it was set to a valid directory.

There are other issues where trying to update the catalog ( etc ...) cause an unwanted log out.

Anyone have any ideas how to correct this ?

I am wondering about cookies and or sessions settings ?

Are there PHP settings (outside of my control) which could cause this ?

Are there browser settings on my side which could be related ?

thanks in advance
Tom

Could be an incompatibility between a new version of PHP with that very old version of Zencart.

The best advice I can offer is to upgrade Zencart right away, for this and many other reasons.