This viewer was promoted from a Project Viewer to an RC viewer today. This viewer has fixes for some attachment-related issues, particularly when multiple attachments are added or removed at the same time. It also has enhanced logging, so your SecondLife.log file will have some additional lines related to avatar state in general and attachments in particular.
Being promoted from Project to RC means this version is closer to what will eventually be released as the main default viewer. It will also likely be more stable than it was as a Project Viewer. So, if you have been having attachment issues, this is probably the viewer to try to solve your problems.