Supplier Name field disappears - URGENT

I am busy capturing supplier invoices.
After capturing about 2 or 3 invoices, when I reenter the supplier invoice page and do a search for the supplier name, either using a wildcard (*) or the supplier full name or a part of the name, the system attempts a search.....only to return with nothing and at the same time the field for supplier name disappears so no further searches are possible

It's making my work very cumbersome and irritating.

Sometimes if I close the browser down, and leave the app for 5 or so minutes, I am able to login again and recommence my capturing . From this is appears to be some kind of handle that is not letting go, or a timeout handle.

I have attempted running on various browsers, but it happens across all of them.
I am running version 2.3.26  running on Ubuntu Linux front end, with a linux backend at my service provider. This occurs on Chromium and firefox browsers.
My internet connection is a 3G wireless link with speeds around 1,5 Mbps

Any advice/ suggestion would be welcome, as I cant afford to waste time like this.....