Thunderbird 45.4.0 not responding

I have TB 45.4.0 running on several Win10 platforms (each with several email accounts), but with one platform it frequently goes "not responding" or tells me that my IMAP server has disconnected when I try to access the inbox folder for a particular account on that platform (however I have no problems with that same inbox/account on other platforms). Other folders in that account on that platform function normally, and other accounts on that platform function normally. I have tried restarting TB in safe mode on that platform with the same results. I have rebuilt the global data base .. with the same results. To reduce workload, have limited synchronization for that account on that platform to only the most current day and have unchecked "Keep Messages on this computer". Yet when I attempt to open a particular message in the inbox folder for that account on that platform TB tells me that it is downloading message XX of YYYY and the numbers do not make any sense. Looking at Tools-> Activity Manager, I see that TB is repeatedly indexing various Sent files of xxxx size, which do not correspond to any of the Sent files for the various TB accounts on this platform. Aside from deleting the offending account and recreating it from my IMAP server, is there any other way to correct this problem?