Errors in my server log

I'm getting loads of error messages in the log such as this:

[13-06-16 08:34:28.2997] Slim::Control::Request::renderAsArray (2269) Error: request should set useIxHashes in Slim::Control::Request->new()
[13-06-16 08:34:28.3003] Slim::Control::Request::renderAsArray (2269) Backtrace:

frame 0: Slim::Utils::Log::logBacktrace (/mnt/USB_SOFTWARE/slimnas/squeezebox/Slim/Control/Request.pm line 2269)
frame 1: Slim::Control::Request::renderAsArray (/mnt/USB_SOFTWARE/slimnas/squeezebox/Slim/Web/Cometd.pm line 939)
frame 2: Slim::Web::Cometd::requestCallback (/mnt/USB_SOFTWARE/slimnas/squeezebox/Slim/Web/Cometd.pm line 792)
frame 3: Slim::Web::Cometd::__ANON__ (/mnt/USB_SOFTWARE/slimnas/squeezebox/Slim/Control/Request.pm line 2083)
frame 4: (eval) (/mnt/USB_SOFTWARE/slimnas/squeezebox/Slim/Control/Request.pm line 2083)
frame 5: Slim::Control::Request::notify (/mnt/USB_SOFTWARE/slimnas/squeezebox/Slim/Control/Request.pm line 861)
frame 6: Slim::Control::Request::checkNotifications (/mnt/USB_SOFTWARE/slimnas/squeezebox/slimserver.pl line 677)
frame 7: main::idle (/mnt/USB_SOFTWARE/slimnas/squeezebox/slimserver.pl line 646)
frame 8: main::main (/mnt/USB_SOFTWARE/slimnas/squeezebox/slimserver.pl line 1180)

Any idea what's wrong and how I fix it?

Thanks