Play with the numbers: When issues aren't wide spread, things get a little trickier. Exactly how Hotmail's load is distributed across the hundreds, if not thousands, of servers they use, is a mystery. If you're able to log in to Hotmail, you'll see addresses like this in your address bar:
The numbers, 18 in this case, will vary, presumably as Hotmail distributes the load by assigning your session to one particular server or set of servers.
In perhaps one of the most obscure ideas I've ever encountered, one reader reported that changing the number (a 2, in his case, to a 23) resolved an issue that was happening after login. Since we have no way of knowing exactly what this really does or why this might work, it's difficult to formally recommend, but you might give it a try if you are able to login and get to an address that looks like that, but then begin having problems. Edit the url directly in the address bar, changing both numbers, and press enter. Who knows? It might work.
If you're used to using your free Hotmail account in Outlook Express, that might be the entire problem. Hotmail support in Outlook Express is being phased out. This Microsoft Knowledgebase Article explains that in order to continue using your Hotmail account in Outlook Express you need to upgrade and purchase an MSN Hotmail Plus account.
Check your clock: make sure that the date and time on your computer are correct. Several aspects of your connection to secure sites like Hotmail rely on your clock being accurate.
The best approach is to use the built-in clock synchronization facility. On Windows XP, right click on the clock in your taskbar, select Adjust Date/Time, click on the Time Zone tab and ensure that the time zone is set correctly. Then click on the Internet Timetab, check Automatically synchronize with an Internet time server. Click Update Now to update the time immediately.