HELP- all browsers evntually freeze and have to reboot

It all started around April 3rd.As far as I know the OS is up to date as far as it will go. Android 4.2.1 'Jelly Bean'. I have 3 browsers: up to date Mozilla Firefox,up to date Yandex, and the original browser set to Bing. In any browser I'll be looking at a web site when it just freezes and no response.Have to push and hold on button or detach pad from keyboard and let battery rundown to off.I don't get it.This epad has worked perfect for 3 years and now seems to be useless as far as getting on the internet.Is that all she rote for this particular model and its now useless for internet useage which is my main reason for its use???

Well I sure wouldn't give up that easily. First try a cold boot, and if that doesn't help, a factory reset. Back up everything first! Procedures for both are in the Master Help Guide, linked in my sig.

In order to get the most possible out of this aging tablet, you have to install a custom ROM. The good news is that the state of development for the 300 is excellent.

Kevin beat me to it. His advice is good.

Not directly related to the freezing problem -- You may have apps auto-starting and hogging resources... I use Greenify to hibernate pesky apps. Also in developer settings you can reduce the number of background processes. AND if your free space on internal storage drops below about 8 GB you will find the device slows down. Good luck.

Another thing you could try is this (short of a full Factory Reset)
Power off and do a cold boot
Go to settings, apps, all
Find each browser in turn and for each...
Clear cache, clear data, force close
Power off and do another cold boot.

See how you get on. If the problem persists, then try the Factory Reset. When you have done it (if you have to) then try running with just the stock browser for a few days. If the problem manifests itself again, then you should either
Manually reinstall the firmware OR
Unlock and install a custom rom.