i need answer please,

hi all , i finished installing php4.3.2 on my server , it is apache 1.3.27; and i checked it , it work good , and when i enabled any dynamic extension , it work good also , but when i enable php_imap.dll in php.ini it gives me this warning: ((( unknown(): unable to load dynamic library 'c:\apache\php\extensions\php_imap.dll' - a device attached to the system is not functioning.))) that is all, and i checked if the php_imap.dll if found in the same folder of extensions, it is there, please tell me what can i do to enable it, good bye, your new member , ahmad.