The newer versions of Simply Accounting use a new kind of database that has lots of problems with Windows Vista. If you get an error message that you can't connect to the Connection Manager, please try:
Add bypass in your Internet Explorer settings
Static vs DHCP IP address
If the proxy bypass for localhost doesn't help, then you should contact Simply Accounting for further assistance. If there is still no progress, a known workaround is to change your computer to use a Static IP address instead of automatic configuration via the DHCP protocol. If you need assistance with this change, you can ask your regular IT technician or hire Caylix helpdesk services for this. Note - this IP change will only work if you have a router in your business or home.