Midi Latency Unless Record Arm is Enabled on track

Hi, first post here. Installed Reaver and used it to rewire with Reason... I press a key and get about a half second delay unless the midi track is armed.. IF the track is armed the latency disappears.. Is there a blindingly obvious reason why that happens? I'm using a delta 1010 pci card and have set Reaver to use the cards asio drivers. Using a sample rate of 44100, block size of 256. I haven't changed any other settings, and when I press the Asio config box, nothing happens. Note on/off on the front panel of my sound card is dead-on, as there is a light that is synchronous with me pressing a key, so I'm not sure where the latency is coming from... any ideas? Thanks in advance. The Pc is up to date and I don't have this problem using Reason in Standalone mode. Hope I've provided enough information for one of you to help

just to mention 

Pc is tweaked for audio, all the usual suspects. Using Reaper 4 with windows 7 64bit sp1. latency is shown as 6.7/6.4 ms at 256 blocks is shown at the top right hand corner of the project

What's Reaver? If you are recording MIDI, the track needs to be record armed and monitor enabled. Block size (aka buffer size) of 256 is a bit high. Plugins can also cause delay also. What else is in the project?

Reaper.. Excuse me, I only downloaded the trial today... This occurs with no other vsts, and is present unless I arm the track. So everybody gets this ?

no, I have to arm the track and then the latency disappears... I have the latest drivers for my soundcard, and no latency when using Reason as a standalone..

Hi there, I downloaded the Reaper trial yesterday to try with my new M-Audio Oxygen 61 keyboard. I'm experiencing a similar delay - new project, single track, no effects (that I know of). Still, a half second latency. The difference in my case is: -Arming the track for recording makes no difference to the latency/delay. -I'm not "rewiring". The midi signal light on the track reacts immediately when I press a key on my keyboard, so I think the USB communication is OK? I tried to download and use the ASIO4ALL driver. But when I use the PC midi instruments, adjusting the buffer size in ASIO4ALL has no effect at all. If I use the synth that comes with Reaper, adjusting the buffer size makes a minimal difference. HP laptop/Win7/IDT audio on board sound card with latest (2010) drivers/USB interface to keyboard. Any help will be greatly appreciated! :-)

Why are you using ASIO4all when native drivers are available.