Apache 2.0.48 disk_cache_module problem: Directory index f..

After hours running apache, disk_cache suddenly causes my root
directory index file (htm) not to load anymore. So I get the error:
'Directory index forbidden by rule:' when trying to access
'mysite.com' without /index.htm. That's right, I forbid root directory
listing via httpd.conf for security reasons. But the index.htm file is
present, why this file is not loading anymore? When I manually empty
the cacheroot (proxy) dir everything returns to be alright. Any idea,
some of my configuration follows, TIA,

Bernhard.

httpd.conf
==========

DirectoryIndex index.htm index.php index.html

<IfModule mod_proxy.c>
ProxyRequests On

<Proxy *>
AuthType Basic
AuthName "Authentication Required"
AuthUserFile
Require user
</Proxy>

ProxyVia on

<IfModule mod_disk_cache.c>
CacheRoot "C:/Program Files/Apache Group/Apache2/proxy"
CacheSize 256
CacheGcInterval 24
CacheEnable disk /
CacheMaxExpire 86400
CacheDefaultExpire 14400
CacheLastModifiedFactor 0.1
CacheDirLength 3
CacheDirLevels 5
</IfModule>

<IfModule mod_mem_cache.c>
CacheEnable mem /
MCacheSize 8192
MCacheMaxObjectCount 100
MCacheMinObjectSize 1
MCacheMaxObjectSize 2048
</IfModule>

</IfModule>
# End of proxy directives.