So it turns out, there were 2 installers - one for XP service pack 2 and XP service pack 3. A friend just tried installing the SP2 installer on SP3 and it didn't work. The SP3 installer did work. FYI.
Like others I am badly in need of the old Logmein installer for Wndows XP which you have made available on Dropbox. I do hope you will agree to share this: I may need to reformat and reinstall win xp on my old pc - it needs to be win xp as several of my programs won't run on later versions of Windows and I need remote access to it.
Thanks in advance for your help.