XP Pro SP3

I use a lot of shortcuts via keys, especially for 'secondary' apps., e.g. CharacterMap Pro (usually needed only in Word) via Ctrl+Shft+M or IrfanView via Ctrl+Shft+I.

About half the time the app. starts immediately but t'other half there can be a delay of up to a minute - it's a bit of a nuisance.

I've never managed to see a pattern to this - it'll be OK for several times then go wrong.

Any ideas as to what's causing this, please?