Random Behaviour

Related to my previous post, I’m having further troubles. Namely, that what works on one system, does not on another. At work, I have a p4 desktop running WindowsXP, an IBM ThinkPad iSeries running Windows2K, and a PowerMac G3, running OS9. The desktop is my primary system, and I have various browsers, but run IE 6 (sp1) on it. The latop I use to test IE 5.0 and AOL 7. The Mac has IE 4 & 5, Netscape 4 & 6 and Mozilla. All of them are set to display either 16- or 32-bit color. The project I’m currently working on works on all of them. However, on one of my clients machines, the site is next to illegible due to faintness of text-color on her 1-year-old laptop, running AOL 7. There may be additional problems also. On a similar G3 Mac, there are apparently layout elements missing, also running OS9 and IE 5. I’ve tested this site on 3 other PCs running AOL 7, and 4 other Macs running between OS 8 and 10.2. The site looked & worked as I expected on all of them (although the text definitely is fainter on all laptops, except those with XP & ClearType running). The only definite difference I can think of is that all of these machines I looked have a high-speed connection. However, the average page is size about 35K, which is tiny.

So why the hell won’t the site work as expected on my client’s machines? Understandably, they’re not going to be happy until it does, but I’m frankly at a loss to understand what else I can do? If a layout works in one install of Mac IE 5.1, should it not work on all installs of Mac IE 5.1? If it is fully functional on my install of AOL 7, should it not work on all installs of AOL 7? The site is in Cold Fusion, which is pre-processed at the server, I make use of a couple of Javascript functions, and the site is XHTML 1.0 (transitional) and makes use of CSS – in other words, a standards-compatible site.

Has anyone had experience with this seeming randomness of behaviour? Can anyone see any possible variables here that I’ve missed? Offer any help at all? Anything would be appreciated, as I’m really at a loss of how to fix this issue right now.