Canadian firm RIM said it replaced a switch to restore its BlackBerry Messenger server, but problems persist, Britain\'s The Register reported Wednesday. RIM, also called Research in Motion, said in a letter to business customers that a quarter of its customers were affected by the problems that have made e-mail and text messages intermittently available for three days. The Register said those without their own servers -- a key target audience for RIM -- are the ones most severely affected by the problems. Rival company Apple Inc. is launching its iMessage server service Wednesday.