Since you didn't supply a lot of information regarding the model, etc. of the pc and keyboard, I will give my first and least expensive (for you) troubleshooting tips. I am giving you this information as a gesture of goodwill and happy holidays. I hope this works for you.
1) Try turning the keyboard upside down and lightly tapping it against the desk. Sometimes dirt, dust, crumbs, etc. fall between and under the keys and make the stick.
If this does not resolve the issue, try this:
2) Purchase a can of air and try blowing the air underneath the keys. Same as above, the device may have debris causing the 'weird' issues you are seeing.
I've seen this occur on many occasions. If this does not resolve the issue, please contact me to accept my bid and additional troubleshooting steps.
Regards,
Adrienne