For the past few days (never happened before) my apps started crashing continuously and kernel panic screen started appearing very frequently. I am still wondering what may be the cause of it, then I tested my RAM with Rember, and this log showed up: --- Memtest version 4.22 (64-bit) Copyright (C) 2004 Charles Cazabon Copyright (C) 2004-2008 Tony Scaminaci (Macintosh port) Licensed under the GNU General Public License version 2 only Mac OS X 10.6.5 (10H574) running in multiuser mode Memory Page Size: 4096 System has 2 Intel core(s) with SSE Requested memory: 1184MB (1241964544 bytes) Available memory: 1184MB (1241964544 bytes) Allocated memory: 1184MB (1241964544 bytes) at local address 0x0000000101000000 Attempting memory lock... locked successfully Partitioning memory into 2 comparison buffers... Buffer A: 592MB (620982272 bytes) starts at local address 0x0000000101000000 Buffer B: 592MB (620982272 bytes) starts at local address 0x0000000126037000 Running 1 test sequence... (CTRL-C to quit) Test sequence 1 of 1: Running tests on full 1184MB region... Stuck Address : setting 1 of 16 ok Linear PRN : setting 1 of 16ok Running comparison tests using 592MB buffers... Random Value : ok Compare XOR : ok Compare SUB : ok Compare MUL : ok Compare DIV : ok Compare OR : ok Compare AND : ok Sequential Increment: ok Solid Bits : setting 1 of 64 FAILURE! Data mismatch at local BUFA address 0x0000000120a36ab0, BUFB address 0x0000000145a6dab0 BUFA Data: 0x7cfbffffffffffff, BUFB Data: 0xffffffffffffffff Block Sequential : setting 1 of 256 --- Does this mean I have to change the RAM? Is that the cause of OS crashing? Thanks in advance for all your responses.