Not any more!!! You can now use an "app_config.xml" file instead of an an app_info file. Here is an example of one:
<app_config>
<app>
<name>moo</name>
<gpu_versions>
<gpu_usage>0.5</gpu_usage>
<cpu_usage>0.05</cpu_usage>
</gpu_versions>
</app>
</app_config>

You can see by the line "<gpu_usage>0.5</gpu_usage>" that it is running 2 units at one. IF you want to run for instance 4 units at once you would put 0.25 instead of 0.5. The number you use is a percentage of 1, so running 3 units would 0.33.

This ONLY works for people running Boinc version 7.0.40 or above, which you are. It eliminates the need to keep changing the file as the different projects change their file names, as this file doesn't use them.

ALSO I don't remember if this one works OR if you have to change the moo to dnetc. Try it the way it is and if it doesn't work change the moo to dnetc. ALSO any current units you have could be lost, so be aware of that. They will just be sent to someone else so don't worry too much about them, but it is best to run the cache dry before making any changes. Oh and put the app_config file in the same place as the app_info file, but be sure to remove or rename the app_info file so Boinc doesn't find both.

The app_config.xml does work and the app name does have to be set to dnetc.

I don't know what the problem is on your end but it seems to work fine on my end, here is a link to one of my completed and validated units:
http://moowrap.net/result.php?resultid=12760278

If you scroll to the start of the details you will see that pc is running Boinc version 7.0.25 and I got Credit 6,144.00 using Application version Distributed.net Client v1.03 (ati14).

ps I went back and looked and you are using a more up to date gpu driver than I am, I am using version 11.9 or driver: 1.4.1546, while you are using driver: 1.4.1720. This could be the problem, do you game? If not try rolling back your driver and see if that fixes the problem. Right now I have 9 pc's with their gpu's attached here and all are using at least Boinc version 7.0.25 and are crunching just fine.