CF9 and Fusebox4 cache problem?

We have a strange issue with caching I think as we are trying to upgrade to CF9.

When opening a particular page it  sometimes works and sometimes doesn’t; throwing the error ‘fusebox.circuit  cannot be defined’ (when it definitely is) and the debugging shows  this:

17:06:57.057 -  Application Exception - in D:\Web\dgmproAffiliates\fusebox4.loader.cfmx.cfm :  line 97

            The specified directory D:\Web\dgmproAffiliates\parsed could not be created.

17:06:57.057 -  Application Exception - in D:\Web\dgmproAffiliates\fusebox4.loader.cfmx.cfm :  line 101

            The specified directory D:\Web\dgmproAffiliates\plugins could not be created.

17:06:57.057 -  fusebox.forceLoadException.fuseboxXmlIsNewer - in  D:\Web\dgmproAffiliates\fusebox4.loader.cfmx.cfm : line  145

            fusebox.xml is newer than it's in-memory cache.

17:06:57.057 -  MissingInclude Exception - in D:\Web\dgmproAffiliates\fusebox4.runtime.cfmx.cfm  : line 170

            Could not find the included template ./fusebox.init.cfm.

17:06:58.058 -  Expression Exception - in D:\Web\dgmproAffiliates\fusebox4.parser.cfmx.cfm :  line 117

            Element FUSEBOX.PARSEWITHCOMMENTS is undefined in APPLICATION.

But then if I refresh the page it  works fine.

We have Fusebox4.

Do we need to upgrade Fusebox as this page was working fine when we were on CF6!

Anyone any idea how to fix this?

Thanks