Here are some of the other symbols that you may run in to and what they mean:
T6 - Regulatory Halt, Extraordinary Market Activity
T12 - Information Requested by Listing Market
H4 - Halt, Non-Compliance
H9 - Halt, Filings Not Current
H10 - Halt, SEC Suspension
H11 - Halt, Regulatory Concern
These are the most common symbols that you will encounter. For a full list, you can visit Nasdaq's web site.
When a stock that you are holding is halted, there is really nothing that you can do. You can't buy or sell shares, so there is no point in contacting your broker.
When the stock does re-open for trading, keep in mind that many people will be either frantically buying (if there was good news released) or selling (if there was bad news released). Keep this in mind because if you place a market order, you may end up with a much worse price than if you had waited an hour or so.
Normally a halt will last an hour or two at the most - in rare circumstances, a halt can last for days, weeks and even months.
The only thing that you can do is try not to panic, and wait for the news to get released.
