Groupwise in XP

I am running Groupwise 5 in XP Pro. We do not plan on upgrading to a new version of groupwise because we are migrating to Exchange. However…the problem I am experiencing is when opening Groupise in remote mailbox mode I recieve an error that entapi32.dll is missing or will not start and that I must re-install groupwise. I get the error but I am able to continue working in my mailbox with no apparent problems. I just want to know what causes the error. I did a search for entapi32.dll on google but I do not come up with anything that pertains to me.Has anyone had this happen or does anyone know what causes entapi32.dll errors? Does anyone know what entapi32.dll is? Any help would be appreciated. Thanks in advance!