Usually, if something get's stuck, the computer is usually at fault.
A- Too slow - An old computer might be too slow to catch signals, like Midi commands.
B- System has too many various software competing with the INTerrupts. In other words, some or more software are CPU hungry causing it to slow down.
C- CPU hungry software i.e. Anti-virus. Some AV like Nortons, takes over the system and the more tasks it does, the slower the system becomes
D- Background tasks occuring such as automatic backups.
E- Not enough memory to handle various software in the background - This will cause windows to swap software in and out of virtual memory
F- Disk drives too slow - SSDs are best. The prices have dropped significantly.
G- Virtual memory too low - I personally set the LOW and HIGH amount to the same value (2x physical memory) and not let windows manage the swap size.
H- Possibility that the graphics card is too old/slow. Since these newer DAWs and software instruments require fast graphics, it could cause the system to slow down.
I- Try not to have a mother board with graphics display onboard. This can cause the CPU to be shared with graphics functions.
J- Audio card could also cause some problems. I have an ASIO card (old but quick) which solved some of my problems for sound.
1- Take a look at the task manager to see how much activity the CPU is doing. If it's maxing out, there's your problem.
2- Take a look at physical memory usage. If it's maxed out, you need more memory.
3- If your disk drive is constantly operating, it usually indicates that windows is swapping programs in and out alot. If you have two physical drives, use the one that windows is NOT on as the swap drive. Also, control the amount of swap space yourself and don't let windows handle it since it is constantly shrinking and expanding the space to accommodate the software it's swapping. Set the space to double the physical memory.
4- If your memory isn't dual memory architecture, invest in it. They should be matched sets of ram and one should be in channel A, the other in channel B. This will increase memory access a lot.
This should help narrow down some computer problems that may be causing various midi (and other) problems like screen jittering (freeze/unfreeze on displays) etc. etc.
If expense is an issue, there are many inexpensive parts that are available. I usually stick with ASUS motherboards and Graphics as well as Audio cards. As for antivirus, I use Avira which does the job perfectly and doesn't take over my system.
Good luck
