Using TB 35.1 on Windows 7 Pro. My filters are enabled to act while downloading messages. Many (a dozen or so) of those result in pop-up error messages saying it cannot write to the target folders, and thus, leaves the messages in the in-box. When I apply all-at-once the filters manually to the in-box, there are no problems. The filters are all enabled (of course), and set to run during both downloading (of course) and manually (of course). I have sporadically had this problem before, but recently switched to a new multi-core computer with Win 7 Pro (from and old single-core one on Win XP Pro). Some of the messages do appear to get filtered, so this is not a universal problem, just with certain (but many) messages targeted to certain (but many) folders. All of the folders are in the same directory tree, so it isn't a matter of different drives, or different security settings. I have many different mail accounts, and when TB is first opened, some of them will download messages at the same time. Generally, filters for each account move messages to it's own folders, but there are a few rare exceptions where a message is moved to a folder under a different account. None of the filters related to the problem involve moving messages from multiple accounts to the same folder. The filter logs are enabled, but I do not see any reports of failure to filter any of the messages, only reports about the messages it did move. Some messages get filtered twice, once to set a flag, and another to move it to a folder. Since there is a lot of private info in both the logs and the filters, and they amount to hundreds of messages and hundreds of filters (a filter and folder for each business I correspond with), I'd rather not send any of that out to anyone and especially will not post that to a public forum, but would answer questions concerning them. However I don't see much difference between the messages, filters, and target folders that work, and the ones that don't. I've cleared the log just now, so that the next time I open TB, I can get a clean log of just that event, and not include any of the manual filtering I'm forced to do. Some thoughts on what might be contributing to this problem: Win 7 has much more stringent security. However, if it were simply a security problem, I doubt that manually running the filters would be any different. The new computer has multiple cores, while the old one did not. Thus, I suspect the problem is related to multi-threading. I have over a hundred folders, so the chance of two messages hitting the same folder simultaneously is miniscule, especially with so many different messages filtering to different folders. Could somehow one thread keep a folder locked for a longer period of time? I used to put the TB profile in a Windows Briefcase for syncing, but upon moving to the new computer, it is now an ordinary folder (at least is supposed to be -- could there be some residual stuff left over after copying it to the new computer that prevents more than one thread accessing it at a time? That seemed to be the problem before with the Briefcase -- only one program (maybe thread?) could access at a time.)