He doesn't remember if he had those crashes while saving, says it was a long time ago..
I'm curious; have you turned off user account control, because that can be one nasty vista's feature; it controls all file types that are changed, and it could be preventing s.t.a.l.ke.r. from creating savegame files as you haven't manually allowed it, which could lead to crashes.
If your UAC (user account control) is turned on, you should try following these steps and then see if the problem is fixed:
1. Click Start, click All Programs, click Accessories, click Run, type secpol.msc in the Open text box, and then click OK.
2. From the Local Security Settings console tree, click Local Policies, and then Security Options.
3. Scroll down and double-click User Account Control: Detect application installations and prompt for elevation.
4. From the User Account Control: Detect application installations and prompt for elevation Properties dialog box, click Disabled, and then click OK.
5. Close the Local Security Settings window.