One Table Running Very Slow

I have a mySQL database with about 10 tables. One table (and only one) is extremely slow to add or to edit a record. This database is on my webhosts server.
When selecting a record and clicking on edit... it takes just under 3 minutes to bring up the record in the edit screen! whereas records in my other tables come up almost instantaneously...?? (same problem when I try to add a record). <img src='https://asprunner.com/forums/file.php?topicimage=1&fieldname=question&id=3231&image=1&table=forumtopics' class='bbc_emoticon' alt=':huh:' />
This table does have a primary key that is varchar (25) ... but another table I use has a primary varchar (50) so that doesn't seem to be the problem. All of the mySQL settings are the same among the various tables (decimal 0, don't allow null, etc)... Is there some setting in php that is different for this table and is causing it to run slower?
Any help would be greatly appreciated.
As a sidenote: when I remotely connect to this table (using software: Navicat), I can add and edit records very quickly... so it doesn't seem to be a problem with mySQL.