A Google Maps Help thread has a confirmed bug with Google Maps not working on a certain version of Internet Explorer. The thing is, there are many complaints about it, so it means a lot of people are using that version.
The bug is actually on Internet Explorer's side, in versin IE7(KB927917). When those who are running IE7(KB927917) try to access Google Maps, it simply won't load. The browser will open up an alert that reads:
Internet Explorer can't open this internet site http://maps.google.com
Amanda L. from Google said they are working on a work around for this issue but they do not have an ETA for when it will be fixed. Amanda said:
Thanks for your patience while we sort this out, and thanks for all of the very detailed reports. We've found the issue and are currently working on a fix. Unfortunately I do not have an exact ETA, but it should be soon.
We did identify that this issue only affects unpatched versions of IE7. While we work on releasing a fix, if you are able to update your browser (which is good practice anyway!), you should no longer get this error. Thanks @JThomas13 for posting those helpful articles on how to update.
I'll let you know when I have another update.
Forum discussion at Google Maps Help.