Mac 0S 9.2.2 - IE 5.1.7 - been using for a few years with no problems I now get the message "security failure data encryption failure" when trying to log in some sites (no issue with this one though) any ideas?

IE for Mac is officially dead; Microsoft says so. There has not been any further development for quite awhile and you won't even be able to get tech support from Microsoft's web site, if not now, then within a month. Many web sites have tightened their security and IE simply can't cope. You'll have to use another browser.

If you don't want to upgrade to OS X, there are still many OS 9 browser to choose from. For choices, go here. If the link doesn't work too well, try later. I had problems with the server when I tried this, and it took forever to load. A quick search at Version Tracker produced nothing usable.

Jon's right about the fact that IE, like most other MacOS 9.x browsers, is no longer actively developed and supported. Increasingly, this means that you're going to have problems with web sites that develop beyond the capabilities of these 'static' browsers. I disagree with Jon that there are many browsers available for MacOS 9.x. That may be true in numbers, but in practice there are only a few browsers that will meet most users’ demands, and none of these can handle every web site out there.

In my experience, WaMCom (a souped-up Mozilla 1.3 version, the latest--and last--to run under 9.x) is the best all-round 9.x browser other than IE, but it too is showing the strain. Still, it beats IE in several respects. With the exception of iCab, the other available browsers show this strain more clearly, in addition to other limitations. But even iCab isn’t universally loved, to say the least.

In view of Alternaut's comments about OS 9 browsers (and I thank him for his additional insights that added to my knowledge), you might consider upgrading to OS X. You will have to be sure that your computer can handle it (firmware update, amount of RAM, available hard drive space), but I think that you will be pleased. I liked OS 9, but after learning my way around X, I stopped using 9 and haven't looked back.