jhd 538 4X16 lcd display error

[zeroskj1988]

hello friends, i have a 24v supply. i use lm7812 to convert 24 v to 12 v and drive 12v relay.i then convert 12v to 5v using 7805 and use for pic18f452 and lcd. i have some problem with this lcd. problem is like this.
sometimes some square boxes appear on my lcd and my pic will stuck on that. this will solve only of i turned off and on system. can any body spot error?

confusing fact is that also in this situation,vcc voltage is 5v.

can any body help thanks in advance

 

[skogsjanne]

Do you get the errors when you operate (switch on/off) the relay? In that case you probably have spikes on the 5V supply coming from the relay.