Mike, I would use the JustPath(Application.ServerName) to determine where you are in your app. it's consistent and I've never seen a problem.
For example:

FUNCTION INIT
SET RESOURCE OFF
SET EXCLUSIVE OFF
SET CPDIALOG OFF
SET DELETED ON
SET EXACT OFF
SET SAFETY OFF
SET REPROCESS TO 2 SECONDS
THIS.cAppStartPath = JustPath(Application.ServerName)+"\"
THIS.cAppName = JustStem(Application.ServerName)
* Set paths (adjust per your needs if necessary)
SET DEFA TO THIS.cappstartpath+'data\'+THIS.cAppName+'\'
THIS.cHTMLpath=THIS.cappstartpath+THIS.cAppName+'\HTML\'

>We've experienced a problem with in-process DLLs having their temp file path corrupted. It seems to have something to do with the parent application changing working folders, but we can't verify that 100%.
>
>The SYS(2023) generally returns garbage when this happens. We notice it when we do a:
>
> SELECT READWRITE
>
>or a
>
> SELECT
> USE (DBF()) AGAIN IN 0
>
>And it tells use the file doesn't exist and gives another folder as the path to the file. I assume it's because the real temp path, can't be found because of the corruption and it searches other possible locations. The temp file does actually get created where it's supposed to, but VFP can't find it there to make it read/write.
>
>Anyone know how to fix this?
>Thanks,
>Mike