Introduction
Apparently Microsoft developed a new installation routine for Windows 7 that checks for the native resolution of your monitor during installation. If Windows 7 has a correct display driver at hand during installation, then it will determine which base resolution to set and based on that resolution which DPI setting it will use.
Examples
Example 1: If you have a small 18" LCD monitor with a 1280 x 800 native resolution and install Windows 7 it will determine that your fonts do not have to be resized and will set your default DPI to 100% (default) in the display settings. Your fonts will be displayed at 96 DPI.
Example 2: If you have a bigger 24" LCD monitor running with a 1900 x 1200 resolution and install Windows 7 it will determine that your fonts would be displayed pretty small at 96 DPI and will instead set your default DPI for fonts to 125% (default) in the display settings. The system fonts will be displayed at 120 DPI which is approximately 125% of 96 DPI.
Example 3: If you have a bigger 24" LCD monitor running with a 1280x 800 non-native resolution and install Windows 7 it will determine that your fonts do not have to be resized and will set your default DPI to 100% (default) in the display settings. In this example you will have small fonts when you resize from 100% (default) to 125% DPI.
Example 3's issues explained
Why is this? Well during the installation routine if your default DPI setting was installed at 100% (default) then some of the system fonts are set incorrectly in the registry. These system fonts do not scale like most of the other fonts.
If you resize from 100% to 125% then these system fonts will stay small. This seems to match your issue.
The fonts that are affected by this phenomena are:
- MS Sans Serif 8,10,12,14,18,24
- MS Serif 8,10,12,14,18,24
- Courier 10,12,15
During installation at 100% DPI (or 96 DPI) the registry setting for "MS Sans Serif..." will probably have been set to SSERIFE.FON (language dependent).
Fix
To enable correct scaling to 125% you would have to change the registry setting to SSERIFF.FON as this will allow for correct font scaling at 125%.
Registry
The registry setting you have to change can be found at:
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Fonts\MS Sans Serif 8,10,12,14,18,24
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Fonts\MS Serif 8,10,12,14,18,24
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Fonts\Courier 10,12,15
Windows Default DPI Setting
Now before you go and change anything, have a look at your default DPI setting in the display settings.
If your default DPI setting is 100% (default) then your fonts should be set to the SERIFE variant, which is the correct setting for small monitors that would not scale up to 125%.
If your default DPI setting is 125% (default) then your fonts should be set to the SERIFF variant, which is the correct setting for bigger monitors that can scale up to 125%.
Caution
Depending on the language of your Windows 7 you might find different values for the fonts. Following is a list (possibly not complete) of values available for different languages:
MS Sans Serif
125% DPI font file | 100% DPI font file
---------------------------------------
SSERIFF.FON | SSERIFE.FON
SSERIFFE.FON | SSERIFEE.FON
SSERIFFG.FON | SSERIFEG.FON
SSERIFFR.FON | SSERIFER.FON
SSERIFFT.FON | SSERIFET.FON
SSEF1255.FON | SSEE1255.FON
SSEF1256.FON | SSEE1256.FON
SSEF1257.FON | SSEE1257.FON
SSEF874.FON | SSEE874.FON
MS Serif
125% DPI font file | 100% DPI font file
---------------------------------------
SERIFF.FON | SERIFE.FON
SERIFFE.FON | SERIFEE.FON
SERIFFG.FON | SERIFEG.FON
SERIFFR.FON | SERIFER.FON
SERIFFT.FON | SERIFET.FON
SERF1255.FON | SERE1255.FON
SERF1256.FON | SERE1256.FON
SERF1257.FON | SERE1257.FON
Courier
125% DPI font file | 100% DPI font file
---------------------------------------
COURF.FON | COURE.FON
COURFE.FON | COUREE.FON
COURFG.FON | COUREG.FON
COURFR.FON | COURER.FON
COURFT.FON | COURET.FON
COUF1255.FON | COUE1255.FON
COUF1256.FON | COUE1256.FON
COUF1257.FON | COUE1257.FON
After you have changed the values in the registry, you have to reboot your computer.
Bonus Display Settings (XP Style)
If you are still encountering issues with old programs (like I did with Groupwise) there is an option in the display setting on the right called user defined text size (DPI) to manually enter a text size in DPI. If you click on the XP style... check box in the dialog, you might be able to solve other issues you encounter with older programs.
Additional Resources & Sources
Windows 7, bitmap fonts and Microsoft Dynamics GP
More on Windows 7, bitmap fonts and DPI settings