Solution:

In the example below, it is recommended that you define a new integer variable for the second always block and the simulator will not hang anymore.

integer ii;

...

always @(*)
for(ii=0;ii
rxclk4[ii] = rxclk_250[ii];

...

always @(*)
for(ii=0;ii

txclk4[ii] = txclk_250[ii];

Note: This happens for Verilog-based simulations only.