We had this case while installing Sage 2011, but it is actually related to Install Shield not beeing able to resolve some of the path variables from registry and can occur on various occassions.

After checking installer verbose logs, we have found "0" as value set for some of shell folders variables in systems registry.

Here are the registry locations to check:

[HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\Explorer\User Shell Folders]

[HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\Explorer\Shell Folders]

[HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\User Shell Folders]

[HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\Shell Folders]

Please check if there are no dodgy values set for all paths stated at above locations and if the paths given there exist and have appropirate access rights set.

It is safe to delete values there and leave them blank but "0" is not allowed.

After removing zeroes, sage installation went smoothly.

I hope that helps!

Best

Maciek