Hi Steve,
I know you said you don't have a lot of control over Windows and application settings and so forth, but that is quite an old patch level of saplogon.exe that you are using. The version number you reported indicates you're using SAPGUI 7.30 patch 2, and the latest is patch 8 hotfix 1 (at least as of yesterday). A great many issues have been resolved in the intervening patches, including some about MS Office interaction and so forth, and without having actually looked at the many patch notes, I'd say you should try updating to the latest patch as a first step. Even discounting this current issue, there are many other issues resolved by those patches.
If you aren't ready to distribute a new patch enterprise-wide (which I certainly understand; I struggle with that here, too), you might experiment by just installing it locally on a couple of 'test' workstations to see if it fixes your problem. If it does, then push for a broader distribution on whatever rollout schedule you typically use.
Best regards,
Matt