I had no problem using an earlier version of Sidekick with Windows 95 (leaving Sidekick running in the background 24 hours a day), but had serious memory problems when, with a new computer, I switched to Windows 98 and Sidekick 99. I solved it in part by periodically checking available memory. and rebooting when available memory dropped below 50%. Most recently, with a new computer and using Windows XP and Sidekick 99, I am again having serious memory problems, but I no longer have a simple way to check available memory. Loyal as I have been to Sidekick, I guess I will have to give it up and go over to Outlook for calendaring, though there is apparently no way to export the Sidekick data.